EXTINCT MAMMALIA OF NORTH AMERICA. 427 



The posterior border is embraced by an attempt to form a basal cingulum. The en- 

 amel of the crown is nearly uniformly corrugated, and the wrinkles are much 

 interrupted. The fling, broken at its point, has been about twice the length of the 

 crown, is conical, slightly curved, and feebly gibbous. 



The tooth bears some resemblance to the corresponding ones of the Californian 

 Seal, Arctocephalas monteriensis, and may perhaps belong to a Seal. It approximates 

 in appearance one of the specimens (figure 9, plate XXX) from Charles Co., Md., 

 referred by Prof. Cope to Squalodon menio. It differs, however, in the proportionately 

 greater breadth of the crown, and in possessing acute borders, and an internal 

 swollen base. The enamel is also generally more strongly corrugated. The fang is 

 much shorter, and very much less gibbous. Side by side the two teeth do not appear 

 to belong to the same animal. 



The measurements of the specimen are as follow : 



Length of the crown, 6 lines ; breadth, .5 lines ; thickness, 4 lines. 

 Length of the fang restored, 14 lines ; breadth, 4i lines. 

 Length of the tooth restored, 19 lines. 



BASILOSAURUS. 



Basilosanms cetoides. 



Gigantic hones, Logan : Proc. Geol. Soc. Lend. (1827, 8) 18.34, I, 8-5. 



Badlosaurus, Harlan : Bui. Soc. Geol. de France (1833), 1835, IV, 124; Trans. Amer. Phil. Soc. 

 1834, TV, 397, PI. XX, Figs. 1, 2; Edinb. New Philos. Jour. 1834, XVIH, 29; Trans. Geol. 

 Soc. Penn. 1835, I, 77, 348, PI. XXII— XXIV; Med. Phys. Res. 1835, 337,349, Pis. XXVI 

 —XXVIII ; Pr. Geol. Soc. Lond. (1839) 1842, III, 23 ; Bul. Soc. Geol. de France, 1839, X, 

 89; Lond. and Edinb. Philos. Mag. 1839, XIV, 302; Trans. Geol. Soc. Lond. (1839) 1842, 

 VI, 67. Owen : Pr. Geol. Soc. Lond. (1839) 1842, III, 24 ; Lond. and Edinb. Philos. Mag. 

 1839, XIV, 302. Wailes : Rep. &c. Geol. of Missis. 1854, 277. 



Zeuglodon, Owen: Proc. Geol. Soc. Lond. (1839) 1842, III, 24; Lond. and Edinb. Philos. Mag. 

 1839, XIV, 302. Conrad: Am. Jour. Sc. 1840, XXXVIII, 381. Anon. : Amer. Jour. Sc. 

 1845, XLIX, 218. Meyer: Jahrb. f Min. 1847, 6(39. Hale: Am. Jour. Sc. 1848, VI, 361. 



ZexKjlodon cetoides, Owen : Lond. Edinb. Philos. Mag. 1839, XIV, 302 ; Trans. Geol. Soc. Lond. 

 1841, VI, 69, Pis. VII— IX ; Pala;ontology, 1859, 345 ; Pictet's Traite de Paleont. 1844, 

 317. Mantell : Medals of Creation, 1844, 826. Emmons : Am. Quar. Jour. Agric. 184-5, II, 

 59, 366; 1846, IIL 223, Pis. I, II. Buckley: Am. Jour. Sc. 1846, II, 125, Figs. 1, 2. Gei- 

 nitz: Versteinerungskuude 1846, 56. Miiller: Monatsb. d. Akad. Wissens. Berlin 1847,103. 

 Archiv f Anatomic, 1847, XIV, 363, 377, 378. Carus : Nov. Act. Acad. Nat. Cur. 1850, 

 XXII, 381. 



Zeuglodon Harlani, Dekay : Nat. Hist. New York, Zool. 1842, 123. Wailes : Rep. &c. Geol. 

 Missis. 1854, 278. 



Zygodon, Buckley: Am. Jour. Sc. 1843, XLIV, 409; Edinb. New Phil. Jour. 1843, XXXV, 77. 

 Koch : Jahrb. Min. 1845, 076, in part. 



Hydrarchus Ilarlani, in part of Koch : Kurze Beschreib. d, Hydr. Harl. 1846 ; Jahrb. f. Min. 



