A MONOGRAPH OF ‘THE SEA-SNAKES (HY)VROPHIINAS), 21] 
are intermediate forms which unite the three supposed species, and am opposed to the 
view held by all previous herpetologists that such forms should each rank as species 
apart. This old view seems to me responsible for much of the extreme confusion 
into which the subject has fallen, and this is not surprising since the characters made 
use of to differentiate these pseudo-species are precisely those which I have remarked 
upon above as very variable in individuals of many well defined species of this genus. 
subcincta (Gray).—This species was described over 60 years ago from the solitary 
type in the British Museum which still remains the only specimen known. In Mr. 
Boulenger’s key to the genus Distira (vol. iii, p. 287), it is separated from brugmansit 
on two points, viz., that the neck scales in subcincta are 23 to 25, in brugmansii 27 
to 31, and that the frontal is hardly as long as its distance to the rostral in swbcincta, 
whereas it is as long or longer in brugmansii. To make any reference to the length 
of the frontal as a distinction between these two supposed species amounts to an 
eloquent admission of the extremely close resemblance between them, for the length 
of this shield in brugmansit by Mr. Boulenger’s own showing varies considerably, 
viz., between its distance to the rostral and its distance to the end of the snout. I 
A b € 
Fig. 20.—Distiva subcincta. Atter Gunther, Rept. Brit. Ind., pl. xxv, fig. F. 
can find no points of difference in the two species, nor does Mr. Boulenger mention 
any in his detailed descriptions other than those already referred to, and I cannot doubt 
that this solitary specimen of swbcincta should, therefore, be considered a spiralis vel 
brugmansit. The ‘ow number of neck scales is not by itself sufficient to form the basis 
of a distinct species, and, moreover, agrees with that of some specimens of melano- 
cephalus, which I am unable to separate from sfiralis. 
The colour of swbcincta is unusual, in that there are round costal spots below the 
dorsal bars, a peculiarity, however, not necessarily opposed to its inclusion with spiralis, 
since an exactly similar colour variety is included by Mr. Boulenger with his species 
ornata, a form usually characterised by dorsal bars. 
melanocephalus (Gray), described in 1849 from a single specimen in the British 
Museum, remained the sole representative till rg01._ In that year I saw in Mr. Owston’s 
collection 19 specimens from the Loo Choo Islands which I examined (nine in detail) 
and identified as D. vobusta (Ginther), i.e., brugmansti (Boie). One of these I sent to 
the British Museum and learnt from Mr. Boulenger he considered H. melanocephalus. 
This species, in his catalogue description, differs from brugmansii in two points only, 
viz., that the head and fore-body are smaller and the neck scales fewer in number in 
melanocephalus. 
I have re-examined the specimen I presented to the British Museum, and find 
