THE ANOURA OF NEW BRUNSWICK. 17 



specific recognition. The case is different at present. An im- 

 mense amount of material has been collected from nearly the 

 whole of North America, so that herpetologists are able not only 

 to correct early mistakes but shed new light on the development 

 of species. Hence it becomes an easy matter to trace the re-' 

 lation of local varieties and strongly marked species. The re- 

 cognition of subspecies marks, too, a new departure in natural 

 history, for within a certain range it opens up a wide and inter- 

 esting field for the investigation of the nature of influences modi- 

 fying animal life, a study deprived, heretofore, of its chief at- 

 traction by the custom of attributing specific fixity to every modi- 

 fication of type, even within narrow and superficial limits. 



But it may be asked on whatcommon and unvarying char- 

 acters is the specific identity of all these forms of the Spring 

 Frog to be based ? A few are here indicated. The large, flat, 

 and thickish head ; muzzle narrowed and rounded ; tympanum 

 larger than the eye ; vomerine teeth in roundish and approxi- 

 mated patches between the choanse, but projecting beyond the 

 line joining their posterior borders ; the heel of the extended 

 hind leg never reaching the tip of the snout ; the first and sec- 

 ond joints of the fourth toe unwebbed; the peculiar bifurcation of 

 the dorso-lateral fold at the ty mpanum;the dark line from the com- 

 missure to the humerus ; the yellow blotching of the under jaw; 

 the reticulated yellow throat ; the general size, seldom exceeding 

 three and a half inches ; the aquatic habit and uniform voice. 

 Many of these characters are structural, fairly constant, andAvill 

 be found to afiord a good basis for the diagnosis and classifica- 

 tion of the members of this apparently heterogeneous group. Yet 

 exceptions are not wanting. The so-called R. clamitans has a 

 hint and truncated muzzle, whitish throat, and is somewhat ter- 

 restrial in habit ; while the vomerine teeth of R. fontinalis are, at 

 least in large individuals, more posterior in position. 



In the degree and permanence of those characters which 

 serve to difi'erentiate it from the rest, what is above designated 

 R. dnmitans seems to merit best the distinction of a species, it. 

 7ii(/n'can.s appears to owe its dark colour and excessive mottling 

 of the inferior surface to its habitat ; at least I have never col- 

 lected it except in streams with bottoms of black mud or of 

 ♦equally black moss-grown rocks, where it herds with similarlv 



