430 



A POPULAR TREATISE ON THE COMMON INDIAN 



SNAKES. 



Illustrated by Coloured Plate and Diagrams 



BY 



F. Wall, C.M.G., C.M.Z.S., F.L.S., Lieut.-Colonel, I.M.S. 

 Part XX VII (with Hate XXVII and Diagram.) 



(Continued from page 97 of Volume XXVI.) 



HYDROPHIS SPIRALIS (Shaw). 



The Narrow-ringed Sea-snake. 



History. — The type is the young example collected by Russell, 

 now in the British Museum, labelled from the "Indian Ocean". 

 It was described by Shaw in 1&02. In my monograph of the sea- 

 snakes piiblished by the Asiatic Society of Bengal in 1909 I 

 expressed the opinion that spiralis (Shaw) and brugrnansi (Boie) 

 were identical species; and subsequently in this Journal (Vol. XX, 

 p. 558) in 1911 substantiated this opinion by remarks upon the 

 variations in the lepidosis, and colouration of a brood of 14 } T oung. 

 The snake described by Gray under the name suhcincta, and that by 

 Gunther as longiceps, both known from single specimens in the 

 British Museum, 1 cannot dissociate from this species. Again 

 the snake described by me and christened alcocld in 1906 (memoirs 

 of the Asiatic Society of Bengal) 1 now think cannot be regarded 

 as a species distinct from spiralis. 



Nomenclature, (a) Scientific. — The generic name is from the 

 Greek " hudor " " water ", and " ophis " " snake,'' and the specific 

 title from Latin refers to the decoration of the body. This, however, 

 is in the form of rings rather than spirals. 



(b) English. — The narrow-ringed sea-snake fits this subject, in 

 which the rings so commonly seen in sea-snakes are narrower 

 than in the other species, at any rate those within Indian seas. 



(c) Vernacular. — Tamil fishermen do not discriminate between 

 the various kinds, and call most sea-snakes " kadel n again " or 

 " sea-snake." 



Identification. — The most reliable and at the same time simple 

 way that I can suggest to identify this species is by counting the 

 costal rows two heads-lengths behind the head, and the same distance 

 before the anus. In no other sea-snake (excepting the species of 

 Platurus and II. jerdoni) are the rows posteriorly so few in excess 

 of those anteriorly. In the latter spot they range between 25 and 

 31, and posteriorly only number 2 to G more, whereas in other 

 species the posterior count is from 10 to 20 in excess of the 



