246 Illinois State Laboratory of Natural History. 



Nasal septum with a ridge on each side. Edge of upper jaw 

 serrulate Aspidoist;ctes. 



Nasal septum with no ridges. Edge of upper jaw serrate. 



Amyda. 



ASPIDONEOTBS, WagLER. 



Wagler, Nat. Syst. Amph., 1830, p. 134. 



With a ridge on each side of the nasal septum. Nostrils 

 terminal. Edge of upper jaw serrulate. Head a trifle wider 

 than in Amyda. 



Aspidonectes spinifer, LeS. Soft-shelled Turtle, Leath- 

 er-back. 



Trionyx spiniferus, LeS., Mem. Mus., 1827, XV., p. 258. 

 Aspidonectes spinifer, Agassiz, L., Contr. Xat. Hist. U. S., 1857, 



I., p. 403.— Jordan, Man. Vert. X. U. S., 3d ed., 1880, p. 168.— 



Smith. Geol. Surv. Ohio, Zool. and Bot., IV., 1882, p. 668. 



—Davis and Rice, Bull. 111. State Lab. Nat. Hist., I., No. 5, 



1883, p. 52; Bull. Chicago Acad. Sci., 1883. 



Length about eight inches. Carapace greatly depressed, 

 with a slight, convex, longitudinal ridge anteriorly, with small 

 tubercles on its anterior margin, and in some specimens with 

 the entire surface roughened with small grain-like elevated 

 points. Plastron large, anterior, leaving the posterior legs ex- 

 posed. Head small, pointed, with a fleshy proboscis bearing 

 the nostrils. Horny covering of the jaws concealed at the 

 sides by fleshy lips. Legs strong, anterior pair with several 

 transverse scales above, posterior with a single large scale. 

 Feet with marginal and interdigital webs. Digits 5-5, the 

 first three on each "foot with claws, the remaining two of each 

 foot with no claws and concealed in the webs. 



Color olive-brown above. Carapace with round, brown, 

 pale-margined spots, those nearest the middle being the largest; 

 the margin at the sides and behind })ale, bounded within by 

 a blackish line. A pale stripe, edged with black, extends from 

 the snout to the eye, and behind the latter continues backward 

 and downward to the side of the neck. A similar stri{)e ex- 

 tends backward from each angle of the mouth. Superior sur- 

 face of the neck with small blackish spots; inferior surface of 



