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"A transverse section before the union of the amnion folds, and a longitudinal median section after the union of the fold. a., Anterior end of blastoderm; p.,. posterior end of blastoderm; a.f., in the left-hand figure, the beginning of the amnion fold; am., amnion; a.c., amniotic cavity; s., serosa; ec., ectoderm; ll., lower germinal layer; y., yolk. The amniotic cavity marks the future ventral region of the embryo, so that the yolk mass is dorsal." -Thomson, 1916

Insect Embryo

"A transverse section before the union of the amnion folds, and a longitudinal median section after…

"Acerentomon, a very primitive insect. H, Head; TH.1, TH.2, TH.3, terga of thoracic segments; 1, 2, 3, the thoracic legs; A.1, A.2, A.3, A.4, abdominal appendages; P.A., eighth abdominal tergum; G., genital aperture; AP.P., post-anal appendix." -Thomson, 1916

Acerentomon

"Acerentomon, a very primitive insect. H, Head; TH.1, TH.2, TH.3, terga of thoracic segments; 1, 2,…

"Vertical cross-section of a Trilobite (Calymene). i., Intestine; s., shield; L., endopodite; e., exopodite; b., epipodial parts." -Thomson, 1916

Trilobite

"Vertical cross-section of a Trilobite (Calymene). i., Intestine; s., shield; L., endopodite; e., exopodite;…

"Male of Nymphon. PR., Proboscis; CH., chelophores; P., pedipalps; E., eggs carried on ovigerous legs; A., rudimentary abdomen." -Thomson, 1916

Nymphon Sea Spider

"Male of Nymphon. PR., Proboscis; CH., chelophores; P., pedipalps; E., eggs carried on ovigerous legs;…

"Ideal mollusc. m., Mouth; g.c., cerebral ganglia; c., edges of mantle skirt; z.g., duct of right lobe of digestive gland; s., pericardial cavity; f., edges of shell-sac; v., ventricle of heart; u., nephridium; an., anus; n., posterior part of the foot; l., opening of nephridium; k., genital aperture; g.ab., abdominal ganglion on visceral loop; g.v., visceral ganglion; z.l., left lobe of digestive gland; p., foot; g.pe., pedal ganglion; g.pl. pleural ganglion." -Thomson, 1916

Mollusc Parts

"Ideal mollusc. m., Mouth; g.c., cerebral ganglia; c., edges of mantle skirt; z.g., duct of right lobe…

"Roman snail (Helix pomatia). Note shell covering visceral hump; p.ap., pulmonary aperture (including anus and opening of ureter); f., the foot; g.ap., genital aperture; m., mouth; e., eye on long horn; s.h., one of short horns." -Thomson, 1916

Roman Snail

"Roman snail (Helix pomatia). Note shell covering visceral hump; p.ap., pulmonary aperture (including…

"Vertical section of the shell of a species of Helix. M., Mouth of shell; A., apex; C., columella." -Thomson, 1916

Shell

"Vertical section of the shell of a species of Helix. M., Mouth of shell; A., apex; C., columella."…

"Dissection of snail. T., Short horn; TT., long horn with eye; N., cerebral ganglia; S.G., salivary glands on the crop; F., foot; M., columellar muscle; V.C., visceral coil; O.T., ovotestis; V., ventricle of heart; R. rectum; U., ureter; B.V., blood vessels returning to the auricle from the mantle; A., pulmonary aperture; MA., edge of the mantle." -Thomson, 1916

Dissection

"Dissection of snail. T., Short horn; TT., long horn with eye; N., cerebral ganglia; S.G., salivary…

"The fresh-water mussel...the bivalve in motion in the mud with protruded foot (F.); nonte inhaland and exhalant apertures...u., the umbo." -Thomson, 1916

Freshwater Mussel

"The fresh-water mussel...the bivalve in motion in the mud with protruded foot (F.); nonte inhaland…

"The fresh-water mussel...the inside of the shell (left valve)...u., The umbo; L., the ligament; c.t., lateral teeth; a.a., anterior adductor mark; a.r., mark of protractor of the foot; p.l., pallial line; p.a., posterior adductor mark; p.r., mark of posterior retractor of the foot; A., anterior (the blunter end); P., posterior." -Thomson, 1916

Freshwater Mussel

"The fresh-water mussel...the inside of the shell (left valve)...u., The umbo; L., the ligament; c.t.,…

"The fresh-water mussel...the outside of the shell (right valve)...u., The umbo; L., the ligament; l.g., a line of growth; A., anterior (the blunter end); P., posterior; V., ventral." -Thomson, 1916

Freshwater Mussel

"The fresh-water mussel...the outside of the shell (right valve)...u., The umbo; L., the ligament; l.g.,…

"Diagram of the structure of Sepia. a., Eight short arms around mouth; l.a., one of the two long arms; b., beak of the mouth; c.g., cerebral ganglia, with commissures to the others; E., eye; g., gullet; d.g., digestive gland (the "salivary glands" are not represented); st., stomach; a., anus; sh., shell-sac with sepiostaire; k., kidney; R., reproductive organ; br.h., branchial heart; g., a gill; i.b., ink-bag; m.c., mantle cavity; f., funnel." -Thomson, 1916

Cuttlefish Structure

"Diagram of the structure of Sepia. a., Eight short arms around mouth; l.a., one of the two long arms;…

"Diagram of circulatory and excretory systems in a Decapod-like Sepia. 1, Gill; 2, renal sac; 3, afferent branchial vessel; 4, branchial heart; 5, abdominal vein; 6, heart; 7, viscero-pericardial sac (body cavity); 8, genital organ; 9, posterior aorta; 10, "auricle"; 11, glandular appendix of branchial heart; 12, renal appendices of branchial vein; 13, external aperure of kidney; 14, vena cava; 15, anterior aorta; 16, bifurcation of vena cava; 17, reno-pericardial aperture." -Thomson, 1916

Cuttlefish Circulatory and Excretory Systems

"Diagram of circulatory and excretory systems in a Decapod-like Sepia. 1, Gill; 2, renal sac; 3, afferent…

"'Nurse' of Doliolum mulleri. I., Inhalant, E., exhalant aperture; C., ciliated band round pharynx (P.); En., endostyle; O., "otocyst"; N., nerve-ganglion; H., heart; (E., oesophageal opening; D., stomach; A., anus; Cl., cloaca; DO., dorsal organ; M., muscle bands." -Thomson, 1916

Doliolum Mulleri

"'Nurse' of Doliolum mulleri. I., Inhalant, E., exhalant aperture; C., ciliated band round pharynx (P.);…

"Sexual individual of Doliolum mulleri. G., gonads; B., gill-slits; I., Inhalant, E., exhalant aperture; C., ciliated band round pharynx (P.); En., endostyle; O., "otocyst"; N., nerve-ganglion; H., heart; (E., oesophageal opening; D., stomach; A., anus; Cl., cloaca; DO., dorsal organ; M., muscle bands." -Thomson, 1916

Doliolum Mulleri

"Sexual individual of Doliolum mulleri. G., gonads; B., gill-slits; I., Inhalant, E., exhalant aperture;…

"Diagram of Salpa africana. o.a., Oral aperture; d.t., dorsal tubercle; te., tentacle; g., ganglion; m., muscle bands; atr., atrium; b.v., blood-vessel; an., anus; a.a., exhalant aperture; v.n., visceral nucleus; h., heart st., stolon; d.l., dorsal lamina; E., endostyle; s.n.g., sub-neural gland; ph., pharynx; p.p.b., peri-pharyngeal band." -Thomson, 1916

Salpa Africana

"Diagram of Salpa africana. o.a., Oral aperture; d.t., dorsal tubercle; te., tentacle; g., ganglion;…

"Lateral view of Amphioxus. The notochord runs from tip to tip. t., Tentacular cirri; G., reproductive organs; a.p., atriopore; a., position of anus; 40 and 62, indicate number of myotomes." -Thomson, 1916

Lancelet

"Lateral view of Amphioxus. The notochord runs from tip to tip. t., Tentacular cirri; G., reproductive…

"Partial section of a Vertebrate brain (diagrammatic). OLF., Olfactory lobe; CH., cerebral hemispheres; C., wall of cerebrum cut to show ventricle, behind this the figure is that of a median section; PA., parietal organ arising from thalamencephalon; Pl., pineal organ; INF., infundibulum descending from thalamencephalon; H., hypophysis; OL., optic lobes; CB., cerebellum; CPL., choroid plexus on roof of fourth ventricle; MO., floor of the medulla oblongata; CC., central canal of spinal cord." -Thomson, 1916

Vertebrate Brain

"Partial section of a Vertebrate brain (diagrammatic). OLF., Olfactory lobe; CH., cerebral hemispheres;…

"Diagrammatic section of spinal cord. p.f., Posterior fissure; p.c., posterior column of white matter; d.p.s., dorsal, posterior, sensory or afferent root; g., ganglion; v.a.m., ventral, anterior, motor or efferent root; c.n., compound spinal nerve with branches; s.g., sympathetic ganglion; a.c., anterior column--the anterior fissure is exaggerated; g.c., ganglion cells; g.m., grey matter; w.m., white matter." -Thomson, 1916

Vertebrate Spinal Cord

"Diagrammatic section of spinal cord. p.f., Posterior fissure; p.c., posterior column of white matter;…

"Diagram showing the ear and related parts in a young cat. P., Pinna; Sq., squamosal: E.A.M., external auditory meatus; T., tympanum; M., malleus; I., incus; St., stapes abutting onforamen ovale; B., bulla of tympanic bone; Se., a septum in the bulla; E.T., eustachian tube leading from the tymmpanic cavity to the back of the mouth; B.O., basi-occipital; C., cochlea; S., sacculus; U., utriculus; D.E., ductus endolymphaticus; N., auditory nerve; S.C., semi-circular canal; PE., periotic bone." -Thomson, 1916

Cat Ear

"Diagram showing the ear and related parts in a young cat. P., Pinna; Sq., squamosal: E.A.M., external…

"Diagram of the eye. C., Cornea; a.h., aqueous humour; c.b., ciliary body; l., lens; I., iris; Sc., sclerotic; Ch., choroid; R., retina; v.h., vitreous humour; y.sp., yellow spot; n., optic nerve." -Thomson, 1916

Eye

"Diagram of the eye. C., Cornea; a.h., aqueous humour; c.b., ciliary body; l., lens; I., iris; Sc.,…

"Section through a young newt. c.t., Connective tissue; E., epidermis; D., dermis; S.C., spinal cord; M., muscle; N., notochord; Sh., mesodermic sheath of notochord; K., kidney; l., lung; S., spleen; ST., stomach; Pe., peritoneum; L., liver; d., duct of the pancreas (P); G.B., gall-bladder; V., dorsal aorta." -Thomson, 1916

Newt Anatomy

"Section through a young newt. c.t., Connective tissue; E., epidermis; D., dermis; S.C., spinal cord;…

"Median longitudinal section of anterior region of Myxine. B., Barbule; N., nasal aperture; NT., nasal tube with rings of cartilage; NC., nasal capsule; BR., brain; SC., spinal cord; N., notochord; G., gut; T., cartilage of "tongue"; MU., muscle; NTT., posterior part of nasal sac; TP., a tooth plate; MT., median tooth on roof of mouth (M.)." -Thomson, 1916

Hagfish Anterior

"Median longitudinal section of anterior region of Myxine. B., Barbule; N., nasal aperture; NT., nasal…

"Respiratory system of hag, from ventral surface. b., Barbules; m., mouth opening on ventral surface; g., gullet; g.p'., first gill-pouch, cut open to show internal lamellae; g.p.6, sixth gill-pouch; v., ventricle of heart; ao., aorta; a., common exhalant aperture." -Thomson, 1916

Hagfish Respiratory System

"Respiratory system of hag, from ventral surface. b., Barbules; m., mouth opening on ventral surface;…

"Bdellostoma stouti (Californian hag), enveloped in sheath of mucus. b., barbules e., eyes m. mucus; eg., eggs." -Thomson, 1916

Californian Hagfish

"Bdellostoma stouti (Californian hag), enveloped in sheath of mucus. b., barbules e., eyes m. mucus;…

"The lamprey (Petromyzon marinus). I. Then entire animal; note the seven gill-slits of which the first is marked g.s., the nostril n., and the unpaired median fins. II. Ventral aspect of the head; u.t., upper teeth; l.t., lower teeth; p., the piston in the mouth. III. Upper surface of the head; n., the nostril with the pineal groove behind it; e., the eye." -Thomson, 1916

Sea Lamprey

"The lamprey (Petromyzon marinus). I. Then entire animal; note the seven gill-slits of which the first…

"Under surface of skull and arches of skate. l.1, First labial cartilage; R., rostrum; tr., trabecular region; n.c., nasal capsule; a.o., antorbital cartilage; p.pt.q., palato-pterygo-quadrae; M.c., Meckel's cartilage; h.m., hyo-mandibular; h.br.1-5, hypobranchials; c.br.5, fifth ceratobranchial; c.h., cerato-hyal; l.2-4, labial cartilages." -Thomson, 1916

Skate Skull

"Under surface of skull and arches of skate. l.1, First labial cartilage; R., rostrum; tr., trabecular…

"Side view of skate's skull. l1., First labial cartilage; n.c., nasal capsule; a.o., antorbital; p.pt.q., palato-pterygo-quadrate; M.c., Meckel's cartilage; h.m., hyo-mandibular; e.h., epi-hyal; c.h., cerato-hyal; h.h., hypo-hyal; h.br.1-5, hypobranchials; c.br., ceratobranchial; e.br., epibranchial; p.br.1., first prebranchial; i.h., inter-hyal; m.pt., meta-pterygoid; 2, 5, 7, foramina of exit of the corresponding nerves." -Thomson, 1916

Skate Skull

"Side view of skate's skull. l1., First labial cartilage; n.c., nasal capsule; a.o., antorbital; p.pt.q.,…

Skeleton of skate. nc, nasal capsules; pq, palato-pterygo-quadrate cartilage; M, Meckel's cartilage; hm, hyo-mandibular; h.br., fifth hypobranchial; v.pl., vertebral plate; st, sensory tubes; sc, scapular region; c, coracoid region; p.pt., anterior basal cartilage or pro-pterygium; m.pt., meso pterygium; mt.pt., meta-pterygium; pu., pubic bar; st, stomach; sv, spiral valve of intestine. -Thomson, 1916

Skate Skeleton

Skeleton of skate. nc, nasal capsules; pq, palato-pterygo-quadrate cartilage; M, Meckel's cartilage;…

"Dissection of nerves of skate. CH., Cerebral hemispheres; O.TH., optic thalami; OL., optic lobes; M., medulla; 4v., posterior part of cerebellum, covering fourth ventricle; OB., olfactory bulb; OC., olfactory capsule; SO., superior oblique muscle; E., eye; SR., superior rectus; ER., external rectus; SO.VII., superficial ophthalmic branch of VII.; SO.V., superficial ophthalmic branch of V.; OP., ophthalmicus profundus; A.C., auditory capsule; B.Pl., brachial plexus; R.F., recurrent facial; C.T., chorda tympani; F.P., facial proper; Hy., hyoidean; Hyomn., hyomandibular; E.M., external mandibular; M.M., mandibular muscle; Sp., spiracle; P.sp., prespiracular; Pl., palatine; O.B., outer buccal; Mn., mandibular; Mx., maxillary; I.B., inner buccal; L., lateral branch of X.; Py., pyloric branch; C., cardiac branch." -Thomson, 1916

Skate Nerves

"Dissection of nerves of skate. CH., Cerebral hemispheres; O.TH., optic thalami; OL., optic lobes; M.,…

"Heart and adjacent vessels of skate. v., Ventricle; c.a., conus arteriosus; p.i., posterior innominate; v.a., ventral aorta; a.i., anterior innominate; Th., thyroid; m., mouth; a., auricle; s.v., sinus venosus; s.c., precaval sinus or sinus of Cuvier; h.s., hepatic sinus; j., jugular; br., brachials; cd., cardinal; epg., epigastric." -Thomson, 1916

Skate Heart

"Heart and adjacent vessels of skate. v., Ventricle; c.a., conus arteriosus; p.i., posterior innominate;…

"The haddock. n.a., Nasal apertures (double on each side); d.f.1, d.f.2, d.f.3, dorsal unpaired fins; c.f., the caudal fin of the homocercal tail. b., Barbule; op., operculum covering the four gills; br.m., continuation of the gill-cover forming the branchiostegal membrane; pv.f., pelvic fin (=hind-limb)--note its jugular position in front of p.f., the pectoral fin (=fore-limb)." -Thomson, 1916

Haddock

"The haddock. n.a., Nasal apertures (double on each side); d.f.1, d.f.2, d.f.3, dorsal unpaired fins;…

"External characters of a Teleostean--a carp (Cyprinus carpio). R., Dorsal unpaired fin; S., homocercal caudal fin; A., anal fin; B., B., pectoral and pelvic paired fins. Note also the lateral line and barbule." -Thomson, 1916

Carp

"External characters of a Teleostean--a carp (Cyprinus carpio). R., Dorsal unpaired fin; S., homocercal…

"Section of a Teleostean gill. G.F., Gill-filament; A., artery (venous blood); V., vein (pure blood); G.A., gill-arch." -Thomson, 1916

Teleostean Gill

"Section of a Teleostean gill. G.F., Gill-filament; A., artery (venous blood); V., vein (pure blood);…

"Diagram of Teleostean circulation. A., auricle; V., ventricle; v.a., ventral aorta; a.br., afferent branchials; e.br., efferent branchials; c.c., cephalic circle; e., carotids; A.c.v., anterior cardinal veins; P.C.V., posterior cardinal veins; d.c., ductuss Cuvieri; d.a., dorsal aortaa; c.v., caudal vein; c.a., caudal artery; K., kidney." -Thomson, 1916

Teleostean Circulation

"Diagram of Teleostean circulation. A., auricle; V., ventricle; v.a., ventral aorta; a.br., afferent…

"Young skate. The yolk-sac has been cut off, the yolk-stalk is left. m., Mouth; ol.o., nostril, e.g. "external gills", a., cloaca; c., claspers." -Thomson, 1916

Young Skate

"Young skate. The yolk-sac has been cut off, the yolk-stalk is left. m., Mouth; ol.o., nostril, e.g.…

"Lateral view of dogfish (Scyllium catulus). Note ventral mouth with naso-buccal groove, heterocercal tail, and unpaired fins. gs., Gill-slits; pc., pectoral fins; pv., pelvic fins." -Thomson, 1916

Dogfish

"Lateral view of dogfish (Scyllium catulus). Note ventral mouth with naso-buccal groove, heterocercal…

"Outline of Acanthodes sulcatus. p., Pectoral fins; v., pelvis; a., anal; d., dorsal." -Thomson, 1916

Acanthodes Sulcatus

"Outline of Acanthodes sulcatus. p., Pectoral fins; v., pelvis; a., anal; d., dorsal." -Thomson, 1916

"Larva of Polypterus. e.g., Large external gill of the hyoid arch; Pc., pectoral fins; Pv., pelvic fins. The larva is drawn in a very characteristic attitude." -Thomson, 1916

Polypterus

"Larva of Polypterus. e.g., Large external gill of the hyoid arch; Pc., pectoral fins; Pv., pelvic fins.…

"Lepidosiren showing (Pc.f.) pectoral fin and the tufted pelvic fin (Pv.f.) of the mature male." -Thomson, 1916

South American Lungfish

"Lepidosiren showing (Pc.f.) pectoral fin and the tufted pelvic fin (Pv.f.) of the mature male." -Thomson,…

"Skeleton of Ceratodus fin. a., Central axis; r., radials; h., basal piece." -Thomson, 1916

Queensland Lungfish Fin

"Skeleton of Ceratodus fin. a., Central axis; r., radials; h., basal piece." -Thomson, 1916

"Head region of Protopterus. sn.t., Sensory tubes; l.l., lateral line; e.br., external gills; pc.l., pectoral fin; op., operculum." -Thomson, 1916

African Lungfish Head

"Head region of Protopterus. sn.t., Sensory tubes; l.l., lateral line; e.br., external gills; pc.l.,…

"Larva of Protopterus. e.g., external gills; Pc., pectoral fin; Pv., pelvic fin." -Thomson, 1916

African Lungfish Larva

"Larva of Protopterus. e.g., external gills; Pc., pectoral fin; Pv., pelvic fin." -Thomson, 1916

"Skull of frog. Upper surface-- Pmx., premaxilla; N., nasal; M., maxilla; Sq., squamosal; Q.j., quadrato-jugal; e.o., ex-occipitals; P.f., parieto-frontals; Sph.E., sphenethmoid; P.O., pro-otic." -Thomson, 1916

Upper Surface of Frog Skull

"Skull of frog. Upper surface-- Pmx., premaxilla; N., nasal; M., maxilla; Sq., squamosal; Q.j., quadrato-jugal;…

"Skull of frog. Lower surface-- Pmx., premaxilla; M., maxilla; Q.j., quadrato-jugal; Q., quadrate; Pt., pterygoid; Ps., parasphenoid; P.O., pro-otic; Sp.E., sphenethmoid; Pl., palatine; V., vomer; c., columella." -Thomson, 1916

Lower Surface of Frog Skull

"Skull of frog. Lower surface-- Pmx., premaxilla; M., maxilla; Q.j., quadrato-jugal; Q., quadrate; Pt.,…

"Skeleton of frog. The half of the pectoral girdle, and fore- and hind-limb of the right side are not shown. pmx., premaxilla; m.x., maxilla; n., nasal; sph., sphenethmoid; p.f., parieto-frontal; P.O., pro-otic; pt., pterygoid; q.j., quadrato-jugal; sq., squamosal; Q., quadrate; c., columella auris; A., atlas; t.p., transverse process; S.V., sacral vertebra; U., urostyle; S.sc., supra scapula; H., humerus; R.U., radio ulna; Cp., carpals; Mc., metacarpals; Il., ilium; Is., ischium; F., femur; T.F., tibio-fibula; Ca., calcaneum; As., astragalus; C., calcar; Mt., metatarsals." -Thomson, 1916

Frog Skeleton

"Skeleton of frog. The half of the pectoral girdle, and fore- and hind-limb of the right side are not…

"Pectoral girdle of Rana esculenta. The cartilaginous parts are dotted. Ep., Episternum; om., omosternum; Ep.c., Epicoracoids; st., sternum; x., xiphisternum; cl., clavicle with underlying precoracoid cartilage; co., coracoid; Sc., scapula; S.sc., supra-scapula; Gl., glenoid cavity for humerus." -Thomson, 1916

Frog Pectoral Girdle

"Pectoral girdle of Rana esculenta. The cartilaginous parts are dotted. Ep., Episternum; om., omosternum;…

"Nervous system of frog. 1-10, The cranial nerves; oc., eyes; crb., in front of optic chiasma; to., optic tract; sym., sympathetic system; msp., spinal cord; sp., spinal nerves." -Thomson, 1916

Frog Nervous System

"Nervous system of frog. 1-10, The cranial nerves; oc., eyes; crb., in front of optic chiasma; to.,…

"Longitudinal vertical section of frog embryo, shortly before closure of blastopore. FB., fore-brain; EC., ectoderm; N., notochord; SC., canal of spinal cord; NE., nerenteric canal; B., blastopore; M., mesoderm; P., beginning of pituitary invagination." -Thomson, 1916

Frog Embryo

"Longitudinal vertical section of frog embryo, shortly before closure of blastopore. FB., fore-brain;…

"Dissection of tadpole. DL., Lower lip; H., ventricle of heart; DE., oesophagus; NA., head kidney; A., aorta; K., kidney; KU., ureter; DO., cloaca; LH., hind-limb; KV., opening of ureter into cloaca; GR., genital ridge; GF., fatty body; LF., fore-limb; OG., gills; a, epidermis; b, dermis." -Thomson, 1916

Tadpole Dissection

"Dissection of tadpole. DL., Lower lip; H., ventricle of heart; DE., oesophagus; NA., head kidney; A.,…

"Skull of turtle. "S.O., supra-occipital; PAR., parietal; FR., frontal; P.F., pre-frontal; PO.F., post-frontal; SQ., squamosal; PMX., pre-maxilla; MX., maxilla; J., jugal; Q.J., quadrato-jugal; Q., quadrate; D., dentary; AN., angular; AR., articular; S., surangular." -Thomson, 1916

Turtle Skull

"Skull of turtle. "S.O., supra-occipital; PAR., parietal; FR., frontal; P.F., pre-frontal; PO.F., post-frontal;…

"Pectoral girdle of a Chelonian. G., Glenoid cavity; SC., scapula; P.C., procoracoid fused to the scapula; C., coracoid; E.C., epicoracoid cartilage; L., ligament." -Thomson, 1916

Turtle Pectoral Girdle

"Pectoral girdle of a Chelonian. G., Glenoid cavity; SC., scapula; P.C., procoracoid fused to the scapula;…

"Heart and associated vessels of tortoise. r.a., Right auricle; superior venae cavae (s.v.c.) and inferior vena cava (i.v.c.) enter it. r.v., Right half of ventricle; pulmonary arteries (p.a.) and left aortic arch (l.ao.) leave it; coel., coeliac; d.ao., dorsal aorta. l.a., Left auricle; p.v., pulmonary veins enter it. l.v., Left half of ventricle; right aortic arch (r.ao.), giving off carotids (c.) and subclavians (s.cl.)." -Thomson, 1916

Tortoise Heart

"Heart and associated vessels of tortoise. r.a., Right auricle; superior venae cavae (s.v.c.) and inferior…

"Snake's head. dv., Poison fangs; b., sheath of fang; l., tongue; rl., muscles of tongue." -Thomson, 1916

Snake Head

"Snake's head. dv., Poison fangs; b., sheath of fang; l., tongue; rl., muscles of tongue." -Thomson,…

"Vertical section through backbone and ribs of Chelonian (I.) and Mammal (II.). N.SP., neural spine; N.SC., neural scute; T., tubercle of rib; C.SC., costal scute over rib (R.); CA., capitulum of rib; T.P., transverse process; CE., centrum; NA., cavity of neural canal. In the Chelonian the tubercle abuts against the flattened neural spine, and the capitulum against the transverse process. In the Mammal, the tubercle articulates with the transverse process and the capitulum with the centrum." -Thomson, 1916

Mammal and Chelonian Backbones

"Vertical section through backbone and ribs of Chelonian (I.) and Mammal (II.). N.SP., neural spine;…

"Diagrammatic section of young bird. n., Spinal cord; v., vertebra; r., rib; L., liver; G., gut; som. (dotted), somatic layer of mesoblast; spl. (dotted), splanchnic layer of mesoblast; ao., aorta; R., reproductive organ; K., kidney." -Thomson, 1916

Bird Section

"Diagrammatic section of young bird. n., Spinal cord; v., vertebra; r., rib; L., liver; G., gut; som.…

"A falcon. mn., Mandible; C., cere; N., nostril; E.C., ear covert; th.W., thumb wing; C., wing coverts; D., dorsal coverts; S., secondaries; P., primaries; R., rectrices; A., ankle; Mt., tarso-metatarsus; I., first toe." -Thomson, 1916

Falcon

"A falcon. mn., Mandible; C., cere; N., nostril; E.C., ear covert; th.W., thumb wing; C., wing coverts;…

"Young bearded griffin (Gypaetus barbatus). Showing the feather-tracts or pterylae, for instance those on the breast (PT.). E., ear; P., web or propatagium; TH., thumb; PR., bases of primary feathers; S., bases of secondary feathers; B.S., bare streak without pterylae; CL., cloaca; R., bases of rectrices or tail feathers." -Thomson, 1916

Lammergeier

"Young bearded griffin (Gypaetus barbatus). Showing the feather-tracts or pterylae, for instance those…

"A., Filoplume. B., very young feather within its sheath (sh.); c., the core of dermis; b., the barbs. C., the same, external view." -Thomson, 1916

Feathers

"A., Filoplume. B., very young feather within its sheath (sh.); c., the core of dermis; b., the barbs.…

"Types of feathers. D., Down. 2, Developing feather in sheath (sh.). 3, Covert of heron showing aftershaft (A.S.). 4, Secondary feather of pigeon--C., calamus; A.S., aftershaft; R., rachis; V., vane. 5, Portion of quill showing inferior umbilicus (I.u.), superior umbilicus (S.u.), pith (P.); F., filoplume." -Thomson, 1916

Feather Types

"Types of feathers. D., Down. 2, Developing feather in sheath (sh.). 3, Covert of heron showing aftershaft…