iU THE EEPTILES OF EGYPT. 
The head in all the foregoing modifications of this species (P. hasselquistii) is 
marked more or less by three principal depressions, one situated behind each nostril, 
and the other on the snout before the eyes, and continued on to the forehead. They 
are most feebly marked in the typical form from Egypt, but are more pronounced in 
the Hejaz examples of that group. In the second Phalanx they are more strongly 
developed, but in the Southern Syrian and Eritrean geckos they are less so, whereas 
in the Galilean and Algerian groups they are still more feeble. 
The heads of the two sexes differ from each other, as the head of the male is always 
heavier and broader posteriorly than that of the female, and the extent of this difference 
is illustrated by figs. 10 & 11, Plate VII. I have also figured a female lizard from 
Maskat (PI. VI. fig. 4), which has a head, when viewed from above in outline, not 
unlike that of the male of forma typica (fig. 1), whereas the head of the male is not 
only proportionally larger than that of fig. 4, but is much broader ; and in both, 
instead of being depressed as in Phalanx I., it is much elevated, and in this the Maskat 
geckos resemble the Sinaitic. Alongside of PL VI. fig. 1, I have figured another male, 
fig. 2, which illustrates the variation that may take place in the heads of the same sex. 
The shape of the head of the Medina gecko differs but little from that of the Egyptian 
members of the Phalanx, but is somewhat broader. The greatest amount of variation 
is met with in the heads of the second Phalanx (PI. VI. figs. 4-5 a and PI. VII. 
figs. 6-8). When traced northwards through the Sinaitic Peninsula to Syria, it is 
seen to undergo considerable modifications, culminating in the large, elongately oval 
head of the Mount Carmel individual, which, in its general form, is not a very extreme 
variation on the heads of the Eastern Arabian (Maskat) geckos, which, however, are 
characterized by considerable elevation. 
It will be observed that the nostril in the 24 specimens of the first Phalanx is 
defined by the E. L. 3 N., but that in a specimen from Philae the rostral is excluded 
on one side of the head, so that the nasal formula L. 3 N., so characteristic of the 
tubular-nosed geckos of the second section of the second Phalanx, is produced. This 
is only an individual variation, as in six other specimens from the same locality the 
formula of the nostril of Phalanx typica is adhered to. The specimen also from the 
Mokattam Hills, although it follows the characteristic formula, has the first labial 
entering so feebly into the rim of the nostril that the slightest increase in the size of the 
nasal process of the rostral or in the dimensions of the posterior inferior nasal would have 
excluded it, and the formula E. 3 N." would have resulted. The degree to which the 
nostril is swollen is the subject of a certain amount of variation. In a specimen from 
Edfu it is so little tumid that it may be described as nearly flat, while in one from 
Wadi Haifa it is only slightly swollen compared with the majority of the specimens, 
whereas in the Medina geckos it is more swollen than in the Egyptian. 
The nasal formula of the geckos of the second Phalanx, as in every other detail of 
their structure, is the subject of great variation. Thus in 11 out of 17 specimens 
