210 BULLETIN 160, UNITED STATES NATIONAL MUSEUM 



The various forms that have been enumerated are here interpreted 

 as individual variations. This conclusion has been reached after a 

 critical examination and tabulation of many specimens. No con- 

 stant geographic peculiarities were encountered among the specimens 

 studied. Unique variations in color pattern were found in almost 

 every local series studied, and as none of these variations are exactly 

 alike, it seems necessary to disregard such peculiarities and group 

 all the leopard frogs of North and Central America under one name. 



The ground color of the upperparts varies greatly and is rarely 

 uniform green or brown. There are two prominent dorso-lateral 

 glandular dermal folds, which are either bronze or yellow, sometimes 

 a very light tint of yellow, and which extend almost parallel to each 

 other from the upper eyelid to the sacral region. These folds often 

 become silvery white after long immersion in alcohol, and between 

 them are brown, olive-green, or nearly black spots, which are gener- 

 ally irregular in shape and arrangement. In many instances the 

 arrangement of the darker marldngs on one side is totally different 

 from that on the opposite side. 



A tabulation of the Mexican series of leopard frogs demonstrated 

 the existence of an endless variety of patterns. One of the variants 

 has numerous, closely aggregated, dark spots. On another the dark 

 dorsal spots are unusually elongated, and several spots apparently 

 are fused. Other specimens have small widely separated dark spots. 

 Fourteen frogs have the dorsal dark spots indistinctly outlined, and 

 in a few instances the spots were nearly effaced. A few individuals 

 were noted that have no apparent dark marldngs between the dorso- 

 lateral glandular dermal folds. Large dark dorsal spots with distinct 

 yellow borders were observed on 45 specimens. At least 50 frogs 

 were counted that have the dorsal dark spots distinctly outlined, but 

 on these the light margins are either very narrow or lacking. Wide 

 or narrow transverse dark bars on the hind limbs, which may be 

 continuous or interrupted, occur more frequently than dark oval spots. 

 The dark transverse bars were continuous on 70 individuals and in- 

 terrupted on 35. A dark marbling on the anterior surface of the 

 thigh is quite noticeable on some specimens and in eight instances a 

 dark band was formed. Many of the frogs, however, lack this darker 

 marbling. Most of the specimens have the throat and chest uni- 

 formly light colored, though there were a number of frogs among 

 those examined that have the throat and chest variegated or marbled 

 with some darker color. 



The Mexican specimens generally have an acuminate snout and a 

 rather narrow head. Other specimens taken at the same localities 

 as those with narrow heads, however, have a much wider head and 

 an obtuse snout. One series of 13 specimens from Durango have the 

 skin of the upperparts unusually rough and pustulose. This condi- 



