COLUBER HYDKTJS. 223 



Vallais it is not rare. Freyer includes it among the Eeptiles 

 of Carniola. 



This species appears to require further investigation, as 

 to whether or not it includes two or even more. 



Coluber hydras. 



Tropidonotus hydras, Dum. et Bib. vol. vii. p. 564. 

 Coluber kydrus, Pallas, Zoog. Ross. As. vol. iii. p. 36. 



Description. — Three pre-ocular and four post-ocular plates; 

 tongue very long and black ; the bones of the palate are 

 furnished with about thirty teeth on each side, these are 

 much hooked and very thin ; the dorsal scales are keeled, 

 slightly forked at their free ends, in nineteen longitudinal 

 rows, those next to the abdomen are without keels ; ventral 

 plates, 167 to 180 ; subcaudal, sixty-two to sixty-five pairs ; 

 anal plate double. Closely resembling in shape the C. 

 Natrix and O. Viperinws, and with similar habits. The 

 upper parts of the body are olive-brown, generally with 

 regularly arranged black spots, which are disposed in quin- 

 cunx; these spots are sometimes wanting, when present 

 they are good distinctive marks ; the lower parts are dull 

 yellow, with black, or sometimes, but less commonly, blood- 

 red spots. It is supposed that there are several variations 

 in the colouring, dependent upon climate and age, which 

 have not been accurately defined. 



Entire length, about 3 feet ; tail, about 6 inches. 



Pallas found this Snake frequent around the Caspian, in 

 the Sea itself, as well as in the rivers and salt-marshes 

 adjoining. It is said by M. Nordmann to be very common 

 all through Southern Eussia, and at Odessa to have been 

 observed in pursuit of fish, generally a species of Qobiws. 



