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"Labrax lupus (Bass), an Acanthopteryglan with anterior spinous and posterior soft dorsal fins." — Encyclopedia Britannica, 1893

Bass

"Labrax lupus (Bass), an Acanthopteryglan with anterior spinous and posterior soft dorsal fins." —…

The ventral and dorsal view of the pupa of Erotylus boisduvali, a fungus beetle.

Fungus Beetle Pupa

The ventral and dorsal view of the pupa of Erotylus boisduvali, a fungus beetle.

An illustration of the dorsal view of a stag beetle.

Stag Beetle (Dorsal)

An illustration of the dorsal view of a stag beetle.

A dorsal view of a chiton, showing the eight shell plates. Chitons are small to large, primitive marine mollusks in the class Polyplacophora. There are 900 to 1,000 extant species of chitons in the class, which was formerly known as Amphineura. Chitons have a shell which is composed of eight separate shell plates or valves. These plates overlap somewhat at the front and back edges, and yet the plates articulate well with one another. Because of this, although the plates provide good protection for impacts from above, they nonetheless permit the chiton to flex upward when needed for locomotion over uneven surfaces, and also the animal can slowly curl up into a ball when it is dislodged from the underlying surface. The shell plates are surrounded by a structure known as a girdle.

Chiton (Dorsal)

A dorsal view of a chiton, showing the eight shell plates. Chitons are small to large, primitive marine…

An illustration of an adult horseshoe crab from the dorsal aspect. The horseshoe crab or Atlantic horseshoe crab (Limulus polyphemus) is a marine chelicerate arthropod. Despite its name, it is more closely related to spiders, ticks, and scorpions than to crabs. Horseshoe crabs are most commonly found in the Gulf of Mexico and along the northern Atlantic coast of North America. A main area of annual migration is the Delaware Bay, although stray individuals are occasionally found in Europe.

Horseshoe Crab (Adult)

An illustration of an adult horseshoe crab from the dorsal aspect. The horseshoe crab or Atlantic horseshoe…

An illustration of a young horseshoe crab from the dorsal aspect. The horseshoe crab or Atlantic horseshoe crab (Limulus polyphemus) is a marine chelicerate arthropod. Despite its name, it is more closely related to spiders, ticks, and scorpions than to crabs. Horseshoe crabs are most commonly found in the Gulf of Mexico and along the northern Atlantic coast of North America. A main area of annual migration is the Delaware Bay, although stray individuals are occasionally found in Europe.

Horseshoe Crab (Young)

An illustration of a young horseshoe crab from the dorsal aspect. The horseshoe crab or Atlantic horseshoe…

"Dissected fish. a, air bladder; b, urinary bladder; b, urinary bladder; br, brain; c, spinal cord; d and da, dorsal fins; dv, anal fin; e, body of the vertebra; g, gills receiving the blood from the ventral aorta leading out of the heart h; i, intestine; k, kidney; l, liver; m, spines of the vertebra; n, auricle of the heart; ov, ovary; ovd, oviduct; st, stomach; sp, spleen; u, ureter." —Davison, 1906

Dissected Fish

"Dissected fish. a, air bladder; b, urinary bladder; b, urinary bladder; br, brain; c, spinal cord;…

"Waldheimia flavescens. Interior of dorsal valve. c, c', cardial process; b', hinge-plate; s, dental sockets; l, loop; q, crura; a, a', adductor impressions; c, accessory divaricator; b, peduncle muscles; ss, septum." — Encyclopedia Britanica, 1893

Dorsal Valve

"Waldheimia flavescens. Interior of dorsal valve. c, c', cardial process; b', hinge-plate; s, dental…

"Terebratula virea. Interior of dorsal valve. l, loop; b, hinge-plate; c, cardinal process." — Encyclopedia Britanica, 1893

Dorsal Valve

"Terebratula virea. Interior of dorsal valve. l, loop; b, hinge-plate; c, cardinal process." —…

"Rhynchonella psittacea. Interior of doral valve. s, sockets; b, dental plates; V, mouth; de, labial appendage in itsnatural position; d, appendage extended or unrolled." — Encyclopedia Britanica, 1893

Dorsal Valve

"Rhynchonella psittacea. Interior of doral valve. s, sockets; b, dental plates; V, mouth; de, labial…

Side view of the dorsal vertebra.

Dorsal vertebra

Side view of the dorsal vertebra.

"Entosternum of scorpion (Palamnaeus indus, de Geer); dorsal surface. asp, Paired anterior process of the subneural arch. snp, Sub-neural arch. ap, Anterior lateral process. lmp, Lateral median process. pp, Posterior process. pf, Posterior flap or diaphragm of Newport. m1 and m2, Perforations of the diaphragm for the passage of muscles. DR, the paired dorsal ridges. GC, Gastric canal or foramen. AC, Arterial canal or foramen." — The Encyclopedia Britannica, 1910

Entosternum

"Entosternum of scorpion (Palamnaeus indus, de Geer); dorsal surface. asp, Paired anterior process of…

"Eurypterus Fischeri, Eichwald. Silurian of Rootzikil. Restoration after Schmidt. The dorsal aspect is presented showing the prosomatic shield with paired compound eyes and the prosomatic appendages II. to IV. The small first pair of appendages is concealed from view by the carapace. 1 to 12 are the somites of the opisthosoma; 13, the post-anal spine." — The Encyclopedia Britannica, 1910

Eurypterus Fischeri

"Eurypterus Fischeri, Eichwald. Silurian of Rootzikil. Restoration after Schmidt. The dorsal aspect…

The dorsal surface of the bones in the right foot.

Foot Bones

The dorsal surface of the bones in the right foot.

"Galeodes sp., one of the solifugae. Dorsal view. I to VI, Bases of the prosomatic appendages. o, Eyes. a, Lateral region of the cephalic plate to which the first pair of appendages are articulated. b, Cephalic plate with median eye. c, Dorsal element of somites bearing third and fourth pairs of appendages. d, Second plate of the prosoma with fifth pair of appendages. e, Third or hindermost plate of the prosoma beneath which the sixth pair of legs is articulated. 1, 2, 9, 10, First, second, ninth and tenth somites of the opisthosoma. an, Anus." — The Encyclopedia Britannica, 1910

Galeodes

"Galeodes sp., one of the solifugae. Dorsal view. I to VI, Bases of the prosomatic appendages. o, Eyes.…

"Diagram of the dorsal surface of Limulus polyphemus. oc, Lateral compound eyes. oc', Central monomeniscous eyes. PA, Post-anal spine. I to VI, The six appendage-bearing somites of the prosoma. VII, Usually considered to be the tergum of the genital somite, but suggested by Pocock to be that of the otherwise suppressed praegenital somite. VIII to XIII, The six somites of the mesosoma, each with a movable pleural spine and a pair of dorsal entopophysis or muscle-attaching ingrowths. XIV to XVIII, The confluent or unexpressed six somites of the metasoma." — The Encyclopedia Britannica, 1910

Limulus Polyphemus

"Diagram of the dorsal surface of Limulus polyphemus. oc, Lateral compound eyes. oc', Central monomeniscous…

"Ventral view of the posterior carapace or meso-metasomatic (opisthosomatic) fusion of Limulus polyphemus. The soft integument and limbs of the mesosoma have been removed as well as all the viscera and muscles, so that the inner surface of the terga of these somites with their entopophyses are seen. The unsegmented dense chitinous sternal plate of the metasoma (XIII to XVIII) is not removed." — The Encyclopedia Britannica, 1910

Limulus Polyphemus

"Ventral view of the posterior carapace or meso-metasomatic (opisthosomatic) fusion of Limulus polyphemus.…

"So-called "trilobite stage" of Limulus polyphemus. A, Dorsal; B, ventral view." — The Encyclopedia Britannica, 1910

Limulus Polyphemus

"So-called "trilobite stage" of Limulus polyphemus. A, Dorsal; B, ventral view." — The Encyclopedia…

"The spinal cord and medulla oblongata. A, from the ventral, and B, from the dorsal aspect; C to H, cross-sections at different levels." —Martin, 1917

Medulla Oblongata

"The spinal cord and medulla oblongata. A, from the ventral, and B, from the dorsal aspect; C to H,…

"Diagram showing the muscular system. M, ventral, N, dorsal valve; l, loop; V, mouth; Z, extremity of intestine; a, adductor; c, divaricators; c', accessory divaricators; b, ventral adjustors; c, peduncular muscles; b''', dorsal adjustors; P, peduncle." — Encyclopedia Britanica, 1893

Muscular System

"Diagram showing the muscular system. M, ventral, N, dorsal valve; l, loop; V, mouth; Z, extremity of…

"One of the Deep Layers of Muscles of the Neck and the Back." — Blaisedell, 1904

Muscles of the neck and back

"One of the Deep Layers of Muscles of the Neck and the Back." — Blaisedell, 1904

"The spinal cord and nerve-roots. A, a small portion of the cord seen from the ventral side; B, the same seen laterally; C, a cross-section of the cord; D, the two roots of a spinal nerve; 1, ventral fissure; 2, dorsal fissure; 3, surface groove along the line of attachment of the ventral nerve-roots; 4, line of origin of the dorsal roots; 5, ventral root filaments of spinal nerve; 6, dorsal root filaments; 6', ganglion of the dorsal root; 7, 7', the first two divisions of the nerve-trunk after its formation by the union of the two roots. The grooves are much exaggerated." —Martin, 1917

Nerve Roots

"The spinal cord and nerve-roots. A, a small portion of the cord seen from the ventral side; B, the…

"Development of notochord : msl, mesoblastic skeletogenous layer ; pdc, paired dorsal cartilage; pvc, paired ventral cartilage; ns, neautral spine; na, neutral arch; tp, transverse process; articular process; c, centrum."—Finley, 1917

Development of the notochord

"Development of notochord : msl, mesoblastic skeletogenous layer ; pdc, paired dorsal cartilage; pvc,…

"Argonauta argo, the "Paper Nautilus," female. The animal is represented in its shell, but the webbed dorsal arms are separated from the shell, which they ordinarily embrace." — Encyclopedia Britannica, 1893

Paper Nautilus

"Argonauta argo, the "Paper Nautilus," female. The animal is represented in its shell, but the webbed…

"Fins of Common Perch. D, first dorsal; D', second dorsal; P, pectoral; V, ventral; A, anal; C, caudal." -Whitney, 1911

Fins of Common Perch

"Fins of Common Perch. D, first dorsal; D', second dorsal; P, pectoral; V, ventral; A, anal; C, caudal."…

"Saurus undosquamis, a Malacoptorgian with anterior soft dorsal and additional adipose fin." — Encyclopedia Britannica, 1893

Saurus Undosquamis

"Saurus undosquamis, a Malacoptorgian with anterior soft dorsal and additional adipose fin." —…

"Fig 56 - Axial skeleton, minus the skull, of an owl, Asio wilsonianus, life size; from nature by Dr. R.W. Shufeldt, USA. at, atlas; ax,axis; cv, cervical vertebrae; c, c', cervical ribs, or free pleurapophyses; dv, dorsal vertebrae, excepting the last one, which joins the sacrum; R, two of the six true ribs (pleurapophyses), whereof sr is sacral; u, one of the five uncinate processes or epipleura; cr, two of the six sternal ribs(haemapophyses), whereof the sixth floats; p, pelvic or sacral region of the spine, comprehending one dorsal, and several lumbar, sacral proper, and urosacral vertebrae; I ilium; Is, ischium; P pubis; a, acetabulum; in, ischio-iliac foremen; o, obturator foramen; clv, caudal or coccygeal vertebrae, whereof py is the pygostyle; s, scapula; ohs, os humero-scapulare; cl, clavicle; C, coracoid; S, sternum." Elliot Coues, 1884

Axial Skeleton

"Fig 56 - Axial skeleton, minus the skull, of an owl, Asio wilsonianus, life size; from nature by Dr.…

"The Top of the Skull, showing the Sutures." — Blaisedell, 1904

Top of skull

"The Top of the Skull, showing the Sutures." — Blaisedell, 1904

Side view of the spinal column. Labels: C 1-7, cervical; D 1-12, dorsal; L 1-15 lumbar; S 1, sacrum; Co 1-4, coccygeal.

Side View of the Spinal Column

Side view of the spinal column. Labels: C 1-7, cervical; D 1-12, dorsal; L 1-15 lumbar; S 1, sacrum;…

A lateral view of the spine divided into its cervical, dorsal, and lumbar portions.

Spinal Divisions

A lateral view of the spine divided into its cervical, dorsal, and lumbar portions.

"A fin-spine; one of the unjointed and unbranched sharp bony rays of the fins, such as those the presence of which gives name to the acanthopterygian fishes; a spinous fin-ray, as distinguished for a soft ray." <p>Illustration of the dorsal fins of the acanthopterygian fish.

Ten Spines on the Fins of a Bony Fish

"A fin-spine; one of the unjointed and unbranched sharp bony rays of the fins, such as those the presence…

The posterior (dorsal) surface of the sternum.

Sternum

The posterior (dorsal) surface of the sternum.

"Stylocellus sumatranus, one of the Opiliones; after Thorell. Enlarged. A, Dorsal view; I to VI, the six prosomatic appendages. B, Ventral view of the prosoma and of the first somite of the opisthosoma, with the appendages I to VI cut off at the base; a, tracheal stigma; mx, maxillary processes of the coxae of the 3rd pair of appendages; g, genital aperture. C, Ventral surface of the prosoma and opisthosoma; a, tracheal stigma; b, last somite. D, Lateral view of the 1st and 2nd pair of apendages. E, Lateral view of the whole body and two 1st appendages, showing the fusion of the dorsal elements of the prosoma into a single plate, and of those of the opisthosoma into an imperfectly segmented plate continuous with that of the prosoma." &mdash; The Encyclopedia Britannica, 1910

Stylocellus Sumatranus

"Stylocellus sumatranus, one of the Opiliones; after Thorell. Enlarged. A, Dorsal view; I to VI, the…

The left trapezoid as seen from the above, the inner side, and behind.

Trapezoid

The left trapezoid as seen from the above, the inner side, and behind.

"Restoration of Triarthrus Becki, Green, as determined by Beecher from specimens obtained from the Utica Slates (Ordovician), New York. A, dorsal; B, ventral surface. In the latter the single pair of antennae springing up from each side of the camerostome or hypostome or upper lip-lobe are seen. Four pairs of appendages besides these are seen to belong to the cephalic tergum. All the appendages are pediform and bi-ramose; all have a prominent gnathobase, and in all the exopodite carries a comb-like series of secondary processes." &mdash; The Encyclopedia Britannica, 1910

Triarthrus

"Restoration of Triarthrus Becki, Green, as determined by Beecher from specimens obtained from the Utica…

"Longitudinal section of valves. A, ventral, B, dorsal valves; l, loop; q, crura; ss, septum; c, cardinal process." &mdash; Encyclopedia Britanica, 1893

Valves

"Longitudinal section of valves. A, ventral, B, dorsal valves; l, loop; q, crura; ss, septum; c, cardinal…

Ventral view of the prevertebral muscles.

Vertebral Muscles

Ventral view of the prevertebral muscles.