328 Alexander G. Ruthven, 



Sharp bai'k they gave when alarmed. The older ones were more 

 solitary and were usiially observed singly along the banks of the 

 streams oi' ponds Avliere they had favorite places for hauling up 

 {Fig. 8). A long shallow lagoon near the San Juan River, the 

 Laguna de Chacalapa, literally swarmed witli individuals from one 

 to two meters long. This lagoon contained few if any fish biit opened 

 into a large shallow niarsh that teemed with waterfowl, whicli 

 probably aftorded an abundance of food. 



Dermatentys nuiwii Gray. 



A Single specimen taken in the San Juan River and another 

 dead along the Arroyo Negra at Cuatotolapam. Called "tortuga 

 blanca" by the natives. The latter informed us that the "tortuga 

 blanca" was not uncommon in the San Juan River, but we were 

 unable to secure any other specimens, owing to the high water at 

 this time of the year. 



These 2 specimens are of adult size, and their carapaces measure 

 460 mm in length. The specimen taken in the Sau Juan River had 

 the alimentary tract füll of vegetable matter. 



Staui'ott/2^us tripovcatus (Wiegmannj. 



A live specimen was taken in the San Juan River and the shell 

 of another along the Arroyo Negra, at Cuatotolapam. Said to be not 

 uncommon in the San Juan River. 



The 2 specimens obtained are of about the same size, and the 

 carapace of the larger one measures 374 mm in length. 



Clciudius fingustatus Cope. 



A Single specimen taken at Cuatotolapam. 



The length of the carapace in the specimen obtained is 107,5 mm, 

 the width 70 mm. 



The species is probably not uncommon at Cuatotolapam. The 

 only two specimens observed were found wandering about on land, 

 one on the prairie, July 31, and one in the cane fields, August 9. 

 CoPE^) States that the food is -'small fish, crustaceans, snails etc." 



Geoniyda puiictiilaria aveolata (A. Dumeril). 

 3 specimens from Cuatotolapam. 

 In life, the light marks on the top of the head, viz., two on the 



1) in: Proc. Acad, nat. Sc. Philadelphia, 1865, p. 188. 



