AMERICAN FROGS OF THE GENUS RANA. 439 



body and limbs is well marked in specimens from North America, 

 but I find it absent in those from Florida, Texas, Arizona, Mexico, 

 and Central America. 



There is one character, not previously pointed out as geographically 

 distinctive, which deserves attention. In nearly all specimens from 

 Canada and the United States a well defined light streak extends on 

 each side of the head above the dark or mottled upper lip, from near 

 the end of the snout to the end of the glandular fold behind the mouth; 

 this streak is absent in Arizonian, Texan, Mexican and Central 

 American specimens, or only distinct from below the eye, as in R. 

 paliistris. 



The tibio-tarsal articulation as a rule reaches the tip of the snout or 

 between the eye and the tip of the snout, but sometimes only the eye 

 (Moose Jaw and La Palma), sometimes beyond the tip of the snout 

 (Pensacola, INloon, Hitchcock, La Cumbre de los Arrestados, Coban, 

 Bebedero) . 



Miss Dickerson says R. sphenocephala is "peculiar in possessing a 

 circular white spot at the center of the tympanum." I find this spot 

 quite as sharply defined in specimens from New Jersey, Colorado, and 

 Texas which, having an obtuse snout, do not answer to the definition 

 of R. sphenocephala. 



I am therefore unable to divide the species in minor groups with 

 any precision, and must leave the matter in abeyance for the present. 

 Probably some day it will be possible to draw up satisfactory defini- 

 tions of the varieties, the principal of which would be sphenocephala, 

 Cope, forreri, Blgr., and austricola, Cope {lecontii, Ster., Brocchi, 

 nigricans, Brocchi). Var. austricola appears to differ from var. 

 forreri by its smoother upper parts and its less sharply defined, often 

 much effaced markings. A precise diagnosis of the var. sphenocephala 

 is still a desideratum, as Miss Dickerson's definition, head long and 

 pointed, with the eyes set far back, hind legs unusually long, fingers 

 and toes long and slender, web betv\'een the toes deeply indented, and 

 a circular, clear-cut white spot in the center of the tympanum, seems 

 to me insufficient, in view of the variation in specimens referable to 

 the typical form. 



