THE BATRACIIIA OF NORTH AMERICA. 227 



In general form this auimal is quite elongate, and the tail is consid- 

 erably shorter than the body, measuring one half of the length of the 

 head and body together. The head is a longer or shorter oval in out- 

 line, and the end of the muzzle is rounded, truncate, and projects be- 

 yond the lower jaw to a moderate degree. In profile it is depressed, and 

 the line of the front gradually descends from behind. The fore limb is 

 short, measuring just half the distance between its anterior base and 

 the end of the muzzle. 



The eyes are very small, and are covered by a thin epidermis or 

 cornea. They are situated just one-third the distance between the end 

 of the muzzle and the base of the anterior external branchia. The 

 upper lip is pendulous at the sides of the mouth, overlapping the lower 

 lip. The latter is free and pendulous at the sides, and is bounded be- 

 low at the base by a deep groove, which may or may not bo continuous 

 round the entire chin. Thus it is complete in seven specimens and in- 

 complete in eighteen. Both conditions are seen in specimens from the 

 same locality, as, for instance, those from Riceborough, Ga., and Mata- 

 moros, in Tamaulipas. The external nares are well separated from 

 each other, and are short transverse slits. 



The superior horny sheath is quite short, covering only the premax- 

 illary bone. It has a sharp edge, and is black in color. The lower 

 sheath is much longer, covering the entire edge of the dentary bone. 

 It is also sharp-edged and black. The tooth patches vary in propor- 

 tions in different individuals. They are distinct from each other, but 

 are in contact anteriorly and diverge posteriorly. The teeth are small 

 and acute, and are arranged in numerous transverse rows in each patch. 

 In adult individuals the patches have an oval outline, but their width 

 varies, and in some others and in immature examples they are more or 

 less linear. Thus in one specimen from Matamoros the vomerine teeth 

 are reduced to a line on each side, the two forming a A- In one from 

 (xeorgia the same arrangement occurs, but in a second from the same 

 locality, and in every other respect similar to it, the teeth are in a wide 

 patch. In two others the patch is intermediate in characters. The 

 surface of the tongue is smooth, not displaying plicae or large pappillae. 

 It occupies nearly the entire floor of the mouth. The internal nostrils 

 are each a hole at the exterior side of the parasphenoid patches of teeth, 

 at the point marking the posterior third of their length. 



The fingers are moderately elongate, and are perfectly free from 

 dermal web or border. Their lengths are in order, commencing with 

 the shortest, 5-2-4-3. The third and fourth are sometimes of equal 

 length. 



The branchiae, when fully developed, form a bipinnate frame-work, 

 to which the ultimate fibrilla? are attached ; that is, the primary stem 

 sends a row of secondary branches downwards on each side, and these 

 again ternary branches on each side. To the under side of these the 

 fibrilloe are attached. They are quite short. The entire branchia is 

 short and not produced at the extremity, as is the case with Necturus 



