Amphibians and* Reptiles of Mexico. 329 



occiput and one oii either side Irom tlie frontal region to above the 

 ear, are dark orange red (82); the light spots on the sides of tlie 

 head, viz., on the iipper eyelid and in front of the ear, are pale 

 yellow (221), and the yellow areas on the body are bricht (216). 

 There are no marking-s on the carapace, except in the young specimens; 

 the two young- males (129,5 mm and 148 mm in length) have a rather 

 poorly defined yellow stripe on the lower margin of the first three 

 costals, limited to a trace on the fourth costal. The bridge and 

 raargin of the plastron are clear yellow (about 246), the middle 

 of the plastron light brown (133j to blackish. The ventral face of 

 the marginal« is bluish (267, 272), and generally sliows a faint 

 light stripe. 



M e a s u r e m e n t s. 



Length 129,5 mm 214 mm 148 mm 

 Width 92,3 148 100 



According to our observations this is the common freshwater 

 turtle of the region about Cuatotolapam. Numerous individuals were 

 observed in the Arroyo Negra and in La Laja Creek. 2 specimens 

 were found wandering about on land, on July 15 and August 3. 



Chelydra rossif/nonii (Bocourt). 



3 immature specimens taken at Cuatotolapam. 



Although quite immature (length of carapace 29 — 31 mm), it is 

 not difflcult to identif}^ our specimens as C. rossignonü. There are 

 four chin-barbels, the bridge is about one-seventh of the length of 

 the plastron, and the abdominal scutes are not twice as broad as 

 long. Aside from these structural characters the specimens also 

 differ in color from those of C. serpcntina of the same size that we 

 have examined. The skin of the lower parts with the plastron and 

 ventral surface of the marginals is jet black with pale yellow or 

 orange yellow spots. The black color extends evenly upon the sides 

 of the head except for a trace of a brown band from the eye, and 

 the brown of the top of the head is somewhat spotted with black. 

 In C. serpentina the lower parts are greyish or brownish in the 

 immature individuals, and while the ground color of the sides of the 

 head may be black there is usually a prominent light band from 

 the eye to the angle of the mouth and frequently other light marks 

 on the sides of the muzzle and head. Furthermore, the top of the 



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