LYTOKHTNCHUS DIADEMA. 273 
It will be observed that the Arabian and S. Persian snakes are seemingly distin- 
guished by a larger number of ventrals than those from other localities, but it is quite 
probable that, with additional materials, the supposed difference may disappear. 
In a specimen from Ain Sefra, Algeria, lent to Mr. Boulenger by Professor Doumergue, 
the upper portion of the rostral is not so rounded posteriorly as in the Egyptian speci- 
mens ; but in another, also from Algeria, although this part of the rostral is considerably 
injured, the form of its outline is much the same as in the Egyptian snakes. There 
are slight differences in the relative dimensions of the internasals and prsefrontals, but 
they are too unimportant to call for any more attention than this passing remark. In 
the typical form from Algeria there may be one or two praeoculars, and a subocular 
may be present or absent. In a specimen from Bushi in Southern Persia there is 
one prseocular and one subocular ; and on one side of the head, in an example from 
Maskat, there is the same arrangement, but on the opposite side of the head the latter 
shield is absent, as is the case in a specimen from Ain Sefra. In Egyptian specimens 
and in others from Jaffa thei'e are two praeoculars and one subocular, or, if the latter 
be regarded as prseocular, then there are three praeoculars as stated by Boettger ; the 
size of the loreal also varies, it being larger in some than in others. Only in one 
instance among the specimens that have come under my observation have four labials 
been in contact with the first pair of chin-shields. It is from the neighbourhood of 
the Suez Canal. 
2 N 
