THE CO LU BRINE SNAKES 



2591 



The broad-tailed sea snakes, of which there are three species, con- 



r " stituting the genus Platurus, in general appearance closely resemble 



some of the craits, especially as regards the shape of the skull and the 



scaling of the head and body, but are distinguished by the compression and depth 



of the tail. In the upper jaw, which is very short, there is in the maxilla of each 



side a pair of large grooved fangs, followed by a single very small solid tooth. 



The arrangement of the shields of the head is normal, each nostril being pierced in 



a laterally-placed nasal; the scales on the body are smooth and overlapping, and 



the inferior surface is covered with large shields. Of the three species, the banded 



sea snake (P. laticaudatus) is distinguished by the absence of a keel on the lower 



BLACK-BANDED SEA SNAKE- 



(Two-thirds natural size.) 



surface of the hinder part of the body, and also of an unpaired shield on the 

 muzzle; the scales being arranged in nineteen rows. In color it is olive above and 

 yellowish beneath, with black rings fully equal in width to the light interspaces. 

 Attaining a length of a little over a yard, this species ranges from the Bay of 

 Bengal and the China Sea to Polynesia. An allied but larger species (P. colu- 

 brinus), with the same distribution, is distinguished by the presence of an unpaired 

 shield on the head, and the arrangement of the scales in from twenty-one to twenty- 

 five rows; while the third species (P. schistorhynchus] from the China Sea and 

 Western Pacific differs in having a keel along the hinder half of the lower sur- 

 face of the body. That the broad-tailed sea snakes are the direct descendants of 

 terrestrial forms allied to the craits, is proved by their retention of large inferior 



