412 EXTINCT MAMMALIA OF NORTH AMERICA. 



Geo!. 1831, 206. Meyer: Paloelogica, 1832, 63. Troost : Trans. Geol. Soc. Pcnu. 1835, I, 



144, 336, 347. Dekay: Nat. Hist. N. York, Zool. 1842, Pt. 1, 99. Owen : Am. Jour. Sc. 



1843, XLIV, 341. Pictet: Traite de Paleont. 1844, I, 223. Geinitz : Verstein. 1846, 26 ; 2d 



Ed. 1853, 1, 269. Dickerson : Proc. Ac. Nat. Sc. 1846, 106. Leidy: Proc. Ac. Nat. Sc. 



1852, 117; 1854, 200; Anc. Fauna Neb. 1853, 9; Waile's Rep. &c. Mississippi, 1854, 286 ; 



Mem. Ext. Sloth Tribe, in Smith. Contrib. 1855, 3, 57, Pis. I-XIII, Figs, 1-7, 9-14, 16, 17 ; 



Trans. Am. Phil. Soc. 1860, XI, 107, PI. VI, Fig. 1. Bronu : Leth. Geag. 1856, III, 1009, 



PI. XLV, Fig. 10. Wymau : Hall and Whitney's Rep. Geol. Wise, and Whitney's do. Up. 



Missis. Lead Region, 1862, 422. 

 Megalonyx laqueaius, Harlan : Jour. Ac. Nat. Sc. 1830, VI, 269, Pis. XII-XIV ; Month. Am. 



Jour. Geol. 1831, I, 45, 74. PI. Ill, Figs. 4-6 ; Edinb. New Phil. Jour. 1834, XVII, 357 ; 



Med. Phys. Res. 1835, 273, 319, Pis. XII-XIV, XV, Figs. 5-7 ; Trans. Geol. Soc. Penn. 



1835, 67, 347, PI. XXI ; Am. Jour. Sc. 1843, XLV, 208. Wyman : Ibid. 1850, 58, Figs. 1, 



2. Leidy : Proc. Ac. Nat. Sc. 1852, 117. 

 Aulaxodon s. Fleurodon, Harlan : Jour. Ac. Nat. Sc. 1830, 284 ; Med. Phys. Res. 1835, 330. 

 Aulaxodon speleum, Rafinesque : Atlantic Journal, 1832-3, 28. 

 Megatherium, Rafinesque: Ibidem. 

 Onychotherium, Fischer: Sur la Turquoise, 40; Bibl. Pal. 1834, 135, on authority of Bronn'sLeth. 



Geog. 1856, III, 1010. 

 Megalonyx potens, Leidy : Proc. Ac. Nat, Sc. 1852, 117. 



Remains discovered in Virginia, Kentucky, Tennessee, Mississippi and Alabama. 



Quaternary. 



Megalonyx dissimilis. 



Megalonix, or Megalonyx, Cuvier: An. du Mus. 1804, V, PI. XXIII, Fig. 13; Ossem. Fos. 1812, 



IV, PI. Megal. Fig. 13 ; 4th Ed. 1836, PI. 216, Fig. 13. 

 Megalonyx laqiceatus, Owen : Odentography, 1840-5, II, 21, PI. 80, Fig. 6. 

 Megalonyx dissimilis, "Leidy : Proc, Ac. Nat. Sc. 1852, 117; Anc. Fauna Neb. 1853, 9; Waile's 



Rep. &c. Geol. Missis. 1854, 286 ; Mem. Extinct Sloth Tribe, 1855, 45, 57, PI. XIV, Figs. 



4-8 ; XVI, Figs. 8, 15. 



Indicated by teeth from near Natchez, Mississippi. Quaternary. 



Megalonyx validns. 



Leidy : Proc. Ac. Nat. Sc. 1868, 175. 



This species is indicated by the fragment of a tooth from Harden County, Texas, 

 and was obtained, together with remains of Mastodon, etc., from a bed of clay and 

 sand beneath a bed of bitumen, with which most of the fossils were more or less 

 imbued. The tooth fragment, of which the triturating surface is represented in figure 

 6, plate XXX, resembles most in form the second upper tooth of the Meijalomjx Jef- 

 fersoni, but is much larger than in the mature individuals of that species. The trans- 

 verse diameter is fifteen and one-fourth lines; the antero-posterior eleven and one- 

 half lines. The transverse section is quadrate. The anterior surface is nearly a 

 transverse plane; the posterior surface forms a plane inclining outward; the inner 

 surface is nearly a plane inclining forward ; the outer surface forms, with tho.se in 

 front and behind, a semicircle. The triturating surface is comparatively slightly 



