RHINOPHIS PULNEYENSIS. 187 



longitudinal band, along each side of the front part of the trunk ; a yellowish ring round 

 the root of the tail. 



/3. In female specimens from 9 to 10 inches long the ch-cumference of the body is one- 

 eleventh or one-twelfth of the total length. The caudal shield terminates below in a very 

 indistinct transverse keel ; six divided subcaudals. Brown above, black below, both colours 

 being separated by an irregular yellowish lateral band, which is broken up into a series of 

 spots on the front part of the trunk and more or less continuous posteriorly. 



y. In male specimens from 7 to 8 inches long {Mytilia melanogaster) the circumference of 

 the body is one-tenth or one-eleventh of the total length. The caudal shield terminates 

 below in a distinct transverse keel, with a minute spine on each side ; nine or ten divided or 

 entire subcaudals. Brownish above, with or without dark longitudinal lines ; black below ; 

 an irregular yellowish longitudinal band along each side. 



S. In young specimens from 3^ to 4 inches long the circumference of the body is one- 

 seventh or one-eighth of the total length. The shield and the scales of the tail are as in the 

 specimens described under y. Greyish olive above, each scale •with a blackish dot, the dots 

 forming longitudinal series ; belly and lower part of the sides uniform yellowish ; each 

 scale of the tail with a black central dot. 



Having most carefully examined more than twenty specimens, besides the types oi. Mytilia 

 tevipletonii and Mytilia melanogaster, I cannot arrive at any other conclusion than that these 

 two forms are identical. The principal ground on which both have been separated is the 

 form of the extremity of the caudal shield, which has a slightly spinose transverse keel in 

 younger examples. This keel becomes indistinct with age, so that the extremity of the tail 

 appears more rounded. The coloration of the belly, also, is not a distinctive character in 

 one of the two supposed species ; the British Museum possesses an old example with a 

 rounded caudal shield without keel (as in M. templetonii) but with a black belly (as in 

 M. melanogaster). 



The variation in the comparative thickness of the body is dependent on age, and very 

 remarkable. It appears, from my observations, that young specimens have a comparatively 

 short body, whilst it becomes most slender in middle age ; when the individuals have attained 

 to their full length (13-14 inches) their body increases in thickness, and old individuals are 

 easily distinguished by the stoutness of their habit. 



This is the most common species of Ceylon, 



Rhinophis pulnktensis. (Plate XVII. fig. C.) 



Plectrurus pulneyensisj Beddome, Proc. Zool. Soc. 1863, p. 228. pi. 25. fig. 2. 



Snout rather obtuse ; rostral shield rounded behind, short, its length being one-fourth of 

 that of the head ; it is flat above, not compressed ; vertical as broad as long. Caudal shield 

 very small, about as large as the rostral. Anterior part of the trunk surrounded by nineteen, 

 its middle by seventeen rows of scales. Ventral shields twice as large as the scales of the 

 adjoming series, 175 in number; subcaudals twelve in the male, from six to eight in the 

 female. The circumference of the body is about one-tenth of the total length. Brownish 



2b2 



