U SYSTEMATIC PALEONTOLOGY 



Family SQUALODONTIDAE. 

 This family is peculiar in its group in that it possesses teeth of two 

 kind as in the Archeoceti; the anterior teeth are simple and conical 

 while the posterior or molar teeth are more complex and are two-rooted 

 (there are teeth in the premaxillary). The skull, however, presents the 

 characters of the Odontoceti. There are no living members of this 

 family. 



Genus SQUALODON Giateloup. 



Squalodon atlanticus Leidy. 



Plate X, Figs. 1, 2, 3. 



Macrophoca atlanticus Leidy, 1856, Proc. Acad. Nat. Sci. Phila., voL viii, p. 320. 

 Squalodo7i atlanticns Cope, 18H7, Proc. Acad. Nat. Sci. Phila., vol. xix, pp. 132, 144, 



151, 153. 

 Squalodon ailanticus Leidy, 1869, Jour. Acad. Nat. Sci. Phila., 2nd ser., vol. vii, p. 



416, pi. xxviii, figs. 4-7 ; pi. xxx, fig. 18. 

 Basilosaurus {.?) atlanticus Cope, n. n. 



Description. — The original specimens described as M. atlanticus con- 

 sisted of three molar teeth from Cumberland county. New Jersey. 

 They were described as follows by Leidy in 1856: " Crowns of the molar 

 teeth broader than the length ; laterally compressed conical ; the anterior 

 and posterior borders acute, the former with a series of acute two, and the 

 latter with four conical tubercles having denticulated borders; inner 

 and outer surfaces exceedingly roughened, especially toward the base, 

 by longitudinally acute and broken ridges. Boot composed of an 

 antero-posterior pair of fangs confluent half their length. 



" Length of largest tooth 2| inches ; length of crown 10 lines, breadth 

 12 lines." 



Cope in 1867 described a second specimen from Charles county, 

 Maryland. " At least four of the most posterior molars were inserted 

 in oblique alveolae, overlapping by their anterior fang the inner face 

 of the posterior fang of the tooth in front, anterior to these the 

 alveolae are less oblique, and separated by spaces. The palatal face is 

 moderately convex, while the external surface is divided into two plane 

 faces by an angulated line, which is strong posteriorly, vanishing anter- 

 iorly."' The fragments are said to indicate a cranium about 30 inches 

 long. The teeth " are longitudinally wrinkled and present a thick 



