384 Illinois State Laboratory of Natural Historij. 



Body long and slender. Mouth small, inferior. Tongue 

 free in front and slightly free at sides. Vomerine teeth in two 

 patches, not in contact in front, widely divergent posteriorly. 

 Interral nares outside the patches of teeth. Branchial tufts 

 fimbriated. Tail short, compressed, with a slight dorsal mem- 

 brane. 



The genus includes but the single species described below. 



Siren lacertina, Linn. 



Siren lacertma, Linn., Act. Acad. Upsal. 1766.— Harlan, Jour. 

 Acad. Nat. Sci. Phila., 1826, V. p. 321.— Holbr., N. A. Herp., 

 1842, T., p. 101, pi. .34.— Kaird, Jour. Acad. Nat. Sci. Phila., 

 2d Ser., I., 1849, p. 291.— Dum. et. Bibr., Erp. Gen., 1854, IX., 

 p. 193.— Smith. Tailed Amphibians, 1877, p. 12.— Boulenger, 

 Cat. Batr. Sal. in Coll. Brit. Mus., 2d ed., 1882, Sal. Caudata, 

 p. 87.— Davis and Rice, Bull. 111. State Lab. Nat. Hist., I., 

 No. 5, 1883, p. 6; Bull. Chicago Acad. Sci., 1883. 



Total length from two to three feet. Slender and eel-like. 

 Head rather small, depressed. Ey^ small, embedded, well for- 

 wards. Snout but slightly rounded from side to side, almost 

 truncate. Nostrils inferior, widely separated. Mouth small, 

 inferior, transverse; lower lip marked off by a groove. Lower 

 jaw provided with a black, corneous, sharp-edged covering, like 

 ' he jaws of tadpoles, in place of teeth. Upper jaw with a sim- 

 ilar but smaller plate. Vomerine teeth in two large oblique 

 patches. Three coarsely fimbriate branchial tufts. Branchial 

 opening not large, covered by three free arches, bearing at their 

 inner margins series of short cartilaginous tubercles. The single 

 pair of legs is placed close behind the head. They are rather 

 weak, and bear four small digits which have dark horny tips 

 resembling claws. Vent, a puckered orifice. Tail compressed 

 and tapering towards the tip, with a slight dorsal membranous 

 expansion. 



Color above dusky or black, sometimes with small whitish 

 spots. Beneath bluish black. 



Length from tip of snout to posterior margin of vent, 

 6.87; tail beyond the latter point, 8.37. 



Not uncommon in southern Illinois. N. 111. (Davis and 

 Rice), Alton (Cope), Running Lake, Union Co., Mt. Carmel 

 (Ridgway). 



