82 The Cephalic Veins and Sinuses of Reptiles 
larly, but occasionally they occur in move or less sinuous rows. The 
stratum sculptum is more or less transparent and in places the outlines 
of the underlying cells can be clearly seen. 
A different sculpture occurs in Lacerta, in which Leydig, 73, described 
a system of wave-like ridges on the surface of the pellicula. In Lacerta 
agilis and muralis these ridges are unsymmetrical, with a long slope of 
about 10° on one side while the other side is vertical or overhanging. 
The ridges are generally parallel in direction but adjacent ridges sooner 
or later anastomose, thus dividing the surface of the epidermis into more 
or less linear areas which vary from 10 » to 100 » or more in length and 
from 34 » to 5 win width. The cells underlying the stratum sculptum 
can occasionally be seen also, the edges fitting together without overlap- 
ping. They average about 22 » in diameter and are generally independent 
of the superficial sculpture. 
In sections of the skin the crests of the ridges show a tendency to 
break up into hair-like processes, and this fact suggests the view that the 
ridges are formed by the union of hairs or bristles which were orginally 
scattered over the surface of the pellicula, as are the tubercules of 
Platydactylus. ; 
The disposition of the ridges on the scales of Lacerta is subject to some 
variation in different regions. On the dorsal scales of the trunk they 
are arranged concentrically around the summit of the scale, the long 
slope being directed toward the base of the scale. On the large rectangu- 
lar ventral scales the ridges are generally transverse in direction, with 
the long slope directed forward. In some cases the ridges bend back- 
ward near the lateral margin of the scale and run parallel with the 
edge, thus throwing the long slope toward the trough between the scales. 
On the shields of the head the general disposition of the ridges is simi- 
lar to that just described, but the bending of the ridges at the lateral 
margins of the scale is very pronounced and constant. Moreover, at the 
posterior margin of the shield a similar change of the relations of the 
ridges is to be observed, the ridges bending through 180° in order to 
throw the long slope toward the trough between the shields. This ar- 
rangement is evidently a modification of that which occurs on the ordi- 
nary scales. 
In the trough between the scales the ridges of the pellicula become 
irregular and correspond to the borders of the cells of the stratum in- 
ternum. This relation suggests the kind of sculpture which occurs in 
the Iguanide. 
In this family, as described by Blanchard, 80, the surface of the pelli- 
