266 THE EEPTILES OF EGYPT. 
observed that the extent of the suture formed by the prseocular and the frontal is 
invariably broad in typical Z. ravergieri, and that in not a few cases in its variety 
nummifer the same character is present. Unfortunately a good many blanks occur 
under this column, as Dr. Midler and Professor Boettger, whose observations I have 
incorporated in the table, did not record the condition of that suture in the specimens 
they examined. The former naturalist did not apparently regard any of the shields 
before the eye as suboculars, and therefore when he spoke of 2 & 3 and 3 & 4 prosoculars 
he, in all likelihood, had in the first of these examples a snake with one prseocular on 
one side of the head, the result of the union of two shields, and a subocular below it ; 
while on the opposite side there were two unamalgamated prseoculars and a subocular 
below them. In the second instance, 3 & 4, there were doubtless two prseoculars and 
a subocular on one side, and two prseoculars, a subocular, and a separated-off portion 
of a labial lying alongside the latter. When he and Prof. Boettger enumerate two 
loreals, the second loreal was in all probability a small portion of a labial set free 
and lying in close relation to the loreal, a condition not uncommon in examples of 
this species. With these explanations it will be seen that all the specimens of 
var. nummifer are distinguished by one or two prteoculars and by one loreal only, as in 
ravergieri. The table conclusively proves the specific identity of all the specimens that 
appear in it, but at the same time establishes the desirability of regarding the western 
snakes as constituting a variety distinguished by slight modifications of no great 
stability. 
The number of the upper labials entering the orbit — i. e. whether they are the 5th, 
5th & 6th, and so on — when the normal number 9 is present, depends chiefly on the 
circumstance whether a portion is separated off from the sixth labial or not ; and when 
their number is increased or diminished, the number to be assigned to them depends, of 
course, on whether the increase is due to division of the labials before or behind the 
orbit, and the same holds good of reduction in the number 9 by amalgamation. There 
may also be union of the postoculars or division, and with these facts kept in view 
the variations recorded in the foregoing tables are easily explicable. 
