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Leaves - simple; alternate; edge lobed (edges of the lobes mostly entire, but notched and toothed towards the ends). Outline - narrow oval or broad oval. Base - from long wedge-shape to squared. Ends of lobes and of the teeth pointed and bristle-tipped. Leaf - three to five inches long; both sides bright green, smooth, and shining; downy in the angles of the ribs below. Lobes - seven to nine, usually seven, with the hollows between them broad and round and usually reaching about three fourths of the way or more to the middle rib. The wide type of leaf closely resembles the leaves of the scarlet oak, but it is smaller and usually the hollows reach nearer to the middle rib. Bark - smoothish (comparatively), inner bark reddish. Acorns - numerous, small, on short stems. Cup - top-shaped, shallow, and nearly smooth. Nut - rounded, one half inch long or less, sometimes broader than long, light brown. October. Found - from the valley of the Connecticut to Central New York, southward to Delaware and the District of Columbia; in Southern Wisconsin and southward; usually along streams and on low, wet land. Most common and reaching its finest growth west of the Alleghany Mountains. General Information - A handsome tree forty to sixty feet high, usually with a pointed top and with light and delicate foliage. The wood is rather coarse and not durable. It takes its name of Pin Oak from the peg-like look of the dead twigs and short branches with which the lower parts of the tree are usually set. Quercus, possible from a Celtic word meaning to inquire, because it was among the oaks that the Druids oftenest practised their rites.

Genus Quercus, L. (Oak)

Leaves - simple; alternate; edge lobed (edges of the lobes mostly entire, but notched and toothed towards…

Leaves - simple; opposite; edge lobed, with the lobes very sparingly and coarsely sharp-toothed or the lower pair entire. Outline - rounded, with three to five lobes, usually five, with the hollows between the lobes and between the coarse teeth rounded. Apex - of the lobes, pointed. Base - heart-shaped or nearly squared. Leaf - dark green above; slightly lighter beneath; smooth or somewhat downy on the ribs; closely resembling that of the introduced "Norway Maple" by lacking the latter's milky-juiced leaf-stem. Bark - light gray, usually smoothish when young, becoming rough and scaly. Flowers - yellow-green and very abundant. April, May. Fruit - greenish-yellow, smooth, drooping, on thread-like and hairy stems one to two inches long, with wings about one inch long, broad and slightly spreading. September. Found - from Southern Canada through the Northern States, southward along the Alleghany Mountains, and westward to Minnesota, Eastern Nebraska, and Eastern Texas. Its finest development is in the region of the Great Lakes. It grows in rich woods; often it forms "groves," sometimes extensive forests.

Genus Acer, L. (Maple)

Leaves - simple; opposite; edge lobed, with the lobes very sparingly and coarsely sharp-toothed or the…

Leaves - simple; opposite; edge lobed, with the lobes very sparingly and coarsely sharp-toothed or the lower pair entire. Outline - rounded, with three to five lobes, usually five, with the hollows between the lobes and between the coarse teeth rounded. Apex - of the lobes, pointed. Base - heart-shaped or nearly squared. Leaf - dark green above; slightly lighter beneath; smooth or somewhat downy on the ribs; when heart-shaped, sometimes with overlapping lobes. Seed-wings - set wide apart, but only slightly diverging. Bark - blackish. Flowers - yellow-green and very abundant. April, May. Fruit - greenish-yellow, smooth, drooping, on thread-like and hairy stems one to two inches long, with wings about one inch long, broad and slightly spreading. September. Found - chiefly along streams and in river bottoms, from Western Vermont to Missouri and Northern Alabama. General Information - A tree fifty to eight feet high or more; of very great value in many directions, - as a shade tree, for fuel, for interior finish and the making of furniture, for its ashes, which give large quantities of potash; especially for its sap, which yields the "maple sugar" of commerce. The yield of sugar by an average tree in one season from five to ten pounds.

Genus Acer, L. (Maple)

Leaves - simple; opposite; edge lobed, with the lobes very sparingly and coarsely sharp-toothed or the…

Leaves - compound (odd-feathered, but with the odd leaflet often dwarfed or broken off; leaflets, twenty-one to forty-one); alternate; edge of the leaflets entire, with one or two coarse, blunt teeth at each side of their base. Outline - of leaflet, long egg-shape or lance-shape. Apex - taper-pointed. Base, squared, or heart-shaped. Leaf/Stem - smooth, round, swollen at base. Leaflet/Stems - smooth and short. Leaf - one and a half to six feet long. Leaflets variable, usually about six inches by two and a quarter, rather smooth and thin. Bark - of the trunk, smooth and brown; the new shoots marked with whitish dots. Flowers - in long bunches at the ends of the branches; greenish, and of very disagreeable odor. June, July. Seeds - flat, at the centre of greenish and sometimes pink-tinged wings, in large, loose clusters. October. Found - common in cultivation, and to some extent naturalized. General Information - A large, showy tree (sixty to seventy feet high) of remarkable vigorous and rapid growth. It is a native of China. A Jesuit missionary sent its seeds in 1751 to England. In 1784 it was brought from Europe to the United States, and started near Philadelphia. Also about 1804 it was brought to Rhode Island from South America. But the source of most of the trees now found abundantly in the region of New York is Flushing, Long Island, where it was introduced in 1820. It has been a great favorite, and would deserve to be so still were it not for the peculiar and disagreeable odor of its flowers. Ailanthus, from a Greek word meaning "tree of heaven." Ailanthus - This spelling of the name should rule because so given by its author, although, etymologically, Ailantus would be correct, the native Amboyna name being "Aylanto."

Genus Ailanthus, Desf.

Leaves - compound (odd-feathered, but with the odd leaflet often dwarfed or broken off; leaflets, twenty-one…

The deciduous and permanent teeth, shown as they are placed in the jaw with portions of bone removed to reveal the roots.

The Deciduous and Permanent Teeth

The deciduous and permanent teeth, shown as they are placed in the jaw with portions of bone removed…

Image of teeth in a human jaw. "1, incisors; 2, canine; 3, bicuspids; 4, molars (the molar at the left is the "wisdom tooth); 5, a blood vessel; 6, a nerve." -Foster, 1921

Teeth

Image of teeth in a human jaw. "1, incisors; 2, canine; 3, bicuspids; 4, molars (the molar at the left…

Two teeth of sharks: "436, Carcharodon angustidens; 435, Lamna elegans." -Dana, 1883

Shark Teeth

Two teeth of sharks: "436, Carcharodon angustidens; 435, Lamna elegans." -Dana, 1883

"a, a', impressions of the muscles; p, pallial line; s, bend occupied by the siphon; h, hinge; c, t, t', teeth." -Cooper, 1887

Clamshell

"a, a', impressions of the muscles; p, pallial line; s, bend occupied by the siphon; h, hinge; c, t,…

The skull of a beaver.

Beaver Skull

The skull of a beaver.

"Ventral surface of disc of an Ophiuroid (Ophiothrix fragilis). g., Openings of genital pockets or bursae; m., mouth; v., ventral plates of arms; sp., spines of arms; tf., tube-feet--at the right side these are represented as retracted; o., the opening through which they are protruded; p., plates around mouth bearing the so-called teeth; one of these plates is perforated, and functions as the madreporite." -Thomson, 1916

Ophiuroid

"Ventral surface of disc of an Ophiuroid (Ophiothrix fragilis). g., Openings of genital pockets or bursae;…

"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 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…

"Lower surface of dog's skull. o.c., Occipital condyle; B.O., basioccipital; T., tympanic bulla; m.c., postglenoid process behind fossa for condyle of mandible; B.S., basisphenoid; P.S., base of presphenoid; V., vomer; M.2, second molar; M.1, first molar; Pm. 1-4, premolars, the 4th the large carnassial; c., canine; I.1-3, incisors; Pmx., premaxilla; mx., maxilla; Pal., palatine; J., jugal; A.S., alisphenoid; Pt., pterygoid; Sq., squamosal (the reference line points to the glenoid fossa)." -Thomson, 1916

Dog Skull

"Lower surface of dog's skull. o.c., Occipital condyle; B.O., basioccipital; T., tympanic bulla; m.c.,…

Half of the lower jaw. Labels: a, the base; b, the angle; c, the ramus; d, the condyle; e, the coronaid process; h, the two incisors or cutting teeth; i, one canine; k, two small molar; l, three large molar or grinding teeth.

Lower Jaw

Half of the lower jaw. Labels: a, the base; b, the angle; c, the ramus; d, the condyle; e, the coronaid…

"Toothed.--Cut so as to resemble teeth." -Newman, 1850

Toothed Leaf

"Toothed.--Cut so as to resemble teeth." -Newman, 1850

"Crenae.--Notches, or round teeth, bordering a leaf or the petals of a flower." -Newman, 1850

Crenated Leaf

"Crenae.--Notches, or round teeth, bordering a leaf or the petals of a flower." -Newman, 1850

"Pectinate.--Like the teeth of a comb." -Newman, 1850

Pectinate Leaf

"Pectinate.--Like the teeth of a comb." -Newman, 1850

"Teeth and Scales of Carboniferous Fish." -Taylor, 1904

Carboniferous Fish Fossils

"Teeth and Scales of Carboniferous Fish." -Taylor, 1904

A straight or slightly curved metallic bar, with teeth n one of its edge, adapted to work into the teeth of a wheel or pinion, for the purpose of converting a circular into a rectilinear motion or vice versa.

Machinery Rack

A straight or slightly curved metallic bar, with teeth n one of its edge, adapted to work into the teeth…

An Implement which in its simplest form consists merely of a wooden or iron bar furnished with wooden or iron teeth, and firmly fixed at right angles to a long handle. The horse rake is a larger rake with are drawn by horses.

Horse Rake

An Implement which in its simplest form consists merely of a wooden or iron bar furnished with wooden…

A wheel with pointed and angular teeth, against which a ratchet abuts, used either for converting a reciprocating into a rotatory motion on the shaft to which it is fixed, or for admitting of circular motion in one direction only, as in a winch.

Ratchet Wheel

A wheel with pointed and angular teeth, against which a ratchet abuts, used either for converting a…

Lower jawbone with the teeth.

The lower jaw

Lower jawbone with the teeth.

The internal view of a tooth cut through from the top or crown to the tips of the root. Labels: 1, enamel; 2, dentine; 3, pulp

The Structure of a Tooth

The internal view of a tooth cut through from the top or crown to the tips of the root. Labels: 1, enamel;…

The permanent teeth of the right side. The numbers show at what age they appear. Labels: a, incisors; b, canines; c, premolars; d, molars.

Permanent Teeth

The permanent teeth of the right side. The numbers show at what age they appear. Labels: a, incisors;…

The alveolar process and teeth were ground off until the antrum of highmore was well exposed; its anterior wall was removed.

Antrum of Highmore with Roots of Teeth

The alveolar process and teeth were ground off until the antrum of highmore was well exposed; its anterior…

The adult teeth. Labels: 1, 2, The cutting teeth (incisors). 3, Eyetooth (cuspid). 4,5, Small grinders (bicuspids). 6, 7, 8, Grinders (molars). 9, 9, Neck of the tooth.

The Adult Teeth

The adult teeth. Labels: 1, 2, The cutting teeth (incisors). 3, Eyetooth (cuspid). 4,5, Small grinders…

The image on the left are the teeth of a carnivora or flesh-eating animal. The teeth on the right belong t a insectivora or insect-eating animal. Notice the projecting jaw, the wide mouth, and sharp teeth of the carnivore animal in contrast with the elongated, tapering muzzle and cone-pointed molars of the insectivorous animal.

Comparing Teeth of Carnivora and Insectivora Animals

The image on the left are the teeth of a carnivora or flesh-eating animal. The teeth on the right belong…

The backward and forward movement of the jaws and the great size and strength of the lower jaw, adapt rodents and gnawers to their mode of life, as in the squirrel. Labels: 1, The enamel of the gnawing tooth. 2, The ivory. 3, The lateral furrows of the molar teeth.

The Lower Jaw of a Squirrel

The backward and forward movement of the jaws and the great size and strength of the lower jaw, adapt…

The molar teeth of a human, horse and dog. The first image to the left in a molar tooth of a horse. Labels: 1, The enamel. 2, The ivory. 3, Canals for blood vessels. The center image is a molar tooth of a human. Label: 1, The enamel. 2, The ivory. 3, The cavity containing blood vessels. 4, 5, Artery and nerve. The image on the right is a molar tooth of a dog. Labels: 1, The enamel. 2, The ivory. 3, Cavity for blood-vessels.

Comparison of the Molar Teeth of a Human, Horse, and Dog

The molar teeth of a human, horse and dog. The first image to the left in a molar tooth of a horse.…

A distribution of the fifth pair of nerves. Labels: 1, The orbit for the eye. 2, The upper jaw. 3, The tongue. 4, The lower jaw. 5, The fifth pair of nerves (trigemini). 6, The first branch of this nerves that passes to the eye. 9, 10, 11, 12, 13, 14, Division of this branch. 8, The third branch that is distributed to the tongue and teeth of the lower jaw. 23, The division of this branch (gustatory). 24, The division that is distributed to the teeth of the lower jaw.

The Fifth Pair of Nerves

A distribution of the fifth pair of nerves. Labels: 1, The orbit for the eye. 2, The upper jaw. 3, The…

The teeth of a 6 and a half year old child. Label: I, the incisors; O, the canine; M, the molars; the last molar is the first permanent teeth; F, sacs of the permanent incisors; C, of the canine; B, of the bicuspids; N, of the second molar; the sac of the third molar is empty.

Emergence of Adult Teeth

The teeth of a 6 and a half year old child. Label: I, the incisors; O, the canine; M, the molars; the…

Vertical section of a molar tooth. Labels: a, enamel of the crown, the line of which indicate the arrangement of its columns; b, dentine; c,cement; d, pulp cavity.

Vertical Section of a Molar

Vertical section of a molar tooth. Labels: a, enamel of the crown, the line of which indicate the arrangement…

Well formed jaws, from which the alveolar plate has been removed to expose the developing permanent teeth in their crypt in the jaws.

Development of Permanent Teeth

Well formed jaws, from which the alveolar plate has been removed to expose the developing permanent…

Longitudinal section (A) and transverse section (B) of a human molar tooth. Labels: c, cement; d, dentine; e, enamel; v, pulp cavity

Structure of a Molar

Longitudinal section (A) and transverse section (B) of a human molar tooth. Labels: c, cement; d, dentine;…

A premolar tooth of a cat.

Premolar of a Cat

A premolar tooth of a cat.

Section of a portion of the dentine and cement from the middle of the root of an incisor tooth. Labels: a, dental tubuli ramifying and terminating, some of them in the interglobular spaces b and c, which somewhat resemble bone lacunae; d, inner layer of the cement with numerous closely set canaliculi; e, outer later of cement; f, lacunae; g, canaliculi.

Dentine and Cement

Section of a portion of the dentine and cement from the middle of the root of an incisor tooth. Labels:…

Enamel fibers. A, fragments and single fibers of the transversely striated enamel, isolated by the action of hydrochloric acid. B, surface of a small fragment of enamel, showing the hexagonal ends of the fibers with the darker centers, or not so high calcified.

Enamel Fibers

Enamel fibers. A, fragments and single fibers of the transversely striated enamel, isolated by the action…

Enamel is composed of fine hexagonal fibers which are set on end on the surface of the dentine and fit into corresponding depressions. Shown is a thin section of enamel and a part of the dentine. Labels; a, cuticular pellicle of the enamel (Nasmyth's membrane); b, enamel fibers, or columns with fissures between them and cross striae; c, larger cavities in the enamel, communicating with the extremities of some of the dentinal tubuli.

Section of the Enamel

Enamel is composed of fine hexagonal fibers which are set on end on the surface of the dentine and fit…

The first step in the development of teeth consists in a downward growth from the Rete Malpighi or the deeper layer of stratified epithelium of the mucous membrane of the mouth, which first becomes thickened in the neighborhood of the maxillae now in the course of formation. This development is shown in a section of the upper jaw of a fetal sheep. A- 1, common enamel germ dipping down into the mucous membrane; 2, palantine process of jaw; 3, Reta Malpighi. B- Section similar to A, but passing through one of the special enamel germs here becoming flask-shaped; c, d, epithelium of mouth; f, neck; f', body of special enamel organ; p, papilla; s, dental sac forming; f p, the enamel germ of permanent tooth; m, bone of jaw; v, vessel cut across.

Development of Teeth

The first step in the development of teeth consists in a downward growth from the Rete Malpighi or the…

Part of section of developing tooth of a young rat, showing the mode of deposition of the dentine. Labels: a, outer layer of fully formed dentine; b, uncalcified matrix with one or two nodules of calcareous matter near the calcified parts; c, odontoblasts sending processes into the dentine; d, pulp; e, fusiform or wedge-shape cells found between odontoblasts; f, stellate cells of pulp in fibrous connective tissue. The section is stained in carmine, which colors the uncalcified matrix, but not the calcified part.

Deposition of Dentine

Part of section of developing tooth of a young rat, showing the mode of deposition of the dentine. Labels:…

Vertical transverse section of the dental sac and pulp of a kitten. Labels: a, dental papilla or pulp; b, the cap of dentine formed upon the summit; c, its covering of enamel; d, inner layer of epithelium of the enamel organ; e, gelatinous tissue; f, outer epithelial layer of the enamel organ; g, inner layer, and h, outer layer of dental sac.

Dental Sac and Pulp

Vertical transverse section of the dental sac and pulp of a kitten. Labels: a, dental papilla or pulp;…

Impaction of the upper third molar in the maxilla. B, Impaction of the lower third molar in the mandible.

Impacted Third Molar

Impaction of the upper third molar in the maxilla. B, Impaction of the lower third molar in the mandible.

Illustrating the relationship of the lateral incisor tooth to the palatal cleft. A, Normal hard palate. The premaxilla is stippled; the lateral incisor occurs in the suture between it and the maxilla. B, Double cleft palate, the lateral incisor being situated on the premaxilla to the inner side of the cleft. The septum of the nose is exposed in the cleft between the maxillary bones. C, Double cleft palate, the lateral incisor being situated on the maxilla to the outer side of the cleft.

Incisor Relation to Palatal Cleft

Illustrating the relationship of the lateral incisor tooth to the palatal cleft. A, Normal hard palate.…

"The Staircase-shell is recognized by its deep umbilicus, wide and funnel-shaped, in the interior of which may be seen the little teeth which follow the edge of every turn of the spiral up to the top. The diameter of this shell is sometimes two and a half inches."

Solarium Perpectivum (Bottom View)

"The Staircase-shell is recognized by its deep umbilicus, wide and funnel-shaped, in the interior of…

"The Staircase-shell is recognized by its deep umbilicus, wide and funnel-shaped, in the interior of which may be seen the little teeth which follow the edge of every turn of the spiral up to the top. The diameter of this shell is sometimes two and a half inches."

Solarium Perpectivum (Side View)

"The Staircase-shell is recognized by its deep umbilicus, wide and funnel-shaped, in the interior of…

"The Viperine Snakes have a long, perforated, erectile fang on the maxillary bone, which is extremely short and bears no teeth."

Fer-de-Lance

"The Viperine Snakes have a long, perforated, erectile fang on the maxillary bone, which is extremely…

"When the animal wishes to use these teeth, they issue from this fleshy sheath, somewhat in the same manner as the claws of a cat when about to be used as weapons of offense."

Fangs and Tongue of an Adder

"When the animal wishes to use these teeth, they issue from this fleshy sheath, somewhat in the same…

"The spindle proper is simply the metal rod and horsehoe-shaped piece of wood with its two rows of little hooks or teeth." - Beard, 1906

Diagram of a spindle

"The spindle proper is simply the metal rod and horsehoe-shaped piece of wood with its two rows of little…

Right superior maxillary bone, inner surface.

Superior Maxillary Bone

Right superior maxillary bone, inner surface.

Unworn surfaces of upper and lower permanent incisor teeth, lingual aspect.

Unworn Incisor

Unworn surfaces of upper and lower permanent incisor teeth, lingual aspect.

Median incisor teeth of left side labial (A) and lateral (B) aspects.

Median Incisor Teeth

Median incisor teeth of left side labial (A) and lateral (B) aspects.

Temporary incisor teeth of left side. A, median; B, lateral incisors.

Temporary Incisor

Temporary incisor teeth of left side. A, median; B, lateral incisors.

Canine teeth of left side, labiial (A) and lateral (B) aspects. C, temporary canines.

Temporary Canine

Canine teeth of left side, labiial (A) and lateral (B) aspects. C, temporary canines.

First premolar teeth of left side, labial (A) and lateral (B) aspects.

First Premolar

First premolar teeth of left side, labial (A) and lateral (B) aspects.

Second molar teeth to the left side, labial (A) and lateral (B) aspects.

Second Molar

Second molar teeth to the left side, labial (A) and lateral (B) aspects.

Triturating surfaces of molar teeth of right side. The upper margin of the figures corresponds to the labial surface.

Surface of Molar

Triturating surfaces of molar teeth of right side. The upper margin of the figures corresponds to the…

Temporary molar teeth (A, first; B, second) of left side. Triturating surfaces of crowns also shown.

Temporary Molar

Temporary molar teeth (A, first; B, second) of left side. Triturating surfaces of crowns also shown.

Sagittal section of canine tooth in situ.

Sagittal Section of Canine

Sagittal section of canine tooth in situ.

Longitudinal section of enamel, treated with acid, showing disposition of ranges of enamel prisms (p, p') in striped of Schreger. Left third of figure shows alternative light(s) and dark (s') bands as seen by reflected light.

Longitudinal Section of Enamel

Longitudinal section of enamel, treated with acid, showing disposition of ranges of enamel prisms (p,…

Transverse section of root of lower canine tooth.

Transverse Section of Root of Canine

Transverse section of root of lower canine tooth.