. Comparative dental anatomy. Teeth; Dentistry. THE TEETH OE VERTEBRATES 53 form predominates, as the teeth in these low types are modifications of the simple cone. This is the primitive typal form of tooth from which all later and complex forms were derived. There is considerable variation of the cone, however, in these classes, some fishes, as the Kays, etc., having plates or a pavement of teeth of flattened shape. Others are of cylindrical or prism-like outline, bnt the majority of fishes and reptiles exhibit modi-. Fig. 16.—Roentgenogram of the mandible of a Squirrel (Sciurus niger), showi
. Comparative dental anatomy. Teeth; Dentistry. THE TEETH OE VERTEBRATES 53 form predominates, as the teeth in these low types are modifications of the simple cone. This is the primitive typal form of tooth from which all later and complex forms were derived. There is considerable variation of the cone, however, in these classes, some fishes, as the Kays, etc., having plates or a pavement of teeth of flattened shape. Others are of cylindrical or prism-like outline, bnt the majority of fishes and reptiles exhibit modi-. Fig. 16.—Roentgenogram of the mandible of a Squirrel (Sciurus niger), showing the incisor of continuous growth and brachydont molars and pre- molars. fications of the simple cone, which is employed for prehension only. In the Mammalia there is a greater variety and more complex forms of teeth. These are formed by evolution of the primitive typal cone, by duplication and modification of the cone to form bicuspid, tritubercular, quadritubercular, etc., forms, as of the molars. Teeth are developed from the primitive cone for various functions: thus the incisors are molded from a single cone. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Thompson, Alton Howard, 1849-1914; Dewey, Martin, 1881-. St. Louis, C. V. Mosby
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