ZOOLOGY. 221 
which, as in the Testudinata, the opisthotic separates it. (See figs. 
13, 14, Sq.) In most of the order it has no contact with the parie- 
tal, the parieto-quadrate arch being supported below by the opis- 
thotic, as above pointed out. But in the Rhiptoglossa (Cha- 
mézleo) the squamosal sends along process upwards, which meets 
a prolongation of the parietal, which is however single and median, 
and not bifurcate as is usual. The opisthotic does not rise with it. 
In the Ophiosauri (Amphisbenia), it appears to be wanting, as Miil- 
ler has already indicated ; and there are various stages of reduction 
to be observed among he Typhlophthalm lizards which approach 
them.* In the Aniellide it is wanting, $ 
while it exists ina rudimental state in [9% ly 
the Acontiadide. (Fig. 20, Ramus Cae 
mandibuli, quadrate, and suspensorium 
2 ‘i Fig. 20.— Acontias meleagris, 8. 
of Acontias meleagris, 3 Sq.) tries ; mandible and suspensorium. 
In the Ophidia the squamosal is obviously wanting. . This is 
proven in two ways: first, by the serial homology of the opisthotic, 
from Lacertilia through Pythonomorpha (fig. 15), or Tortricina (fig. 
16), with the single suspensorium of the quadrate in typical snakes ; 
and, second, by the successive diminution of the squamosal in the 
Lacertilia from the Leptoglossa through the Typhlophthalmi, where 
it is rudimental in Acontias (fig. 19), and wanting in Aniella, and 
‘in the succeeding group of Amphisbenia, Therefore its identifi- 
cation with the suspensorium in Ophidia, proposed by Huxley, 
must be abandoned.t 
Returning to the earlier types of Reptilia, we may recall the 
features of the squamosal already ascribed to the Ichthyopterygia 
and Anomodontia. The first peculiar feature, the anterior prolon- 
gation on each side of the cranium, on the inside of the temporal 
fossa, separating widely the supraoccipital and parietal, was shown 
to exist also in the Rhynchocephalia. The question of the real 
pertinence of this prolongation to the squamosal may be raised, as 
it is remote from the position of that bone in most of the Lacer- 
tilia, and in some specimens of Ichthyosaurus is separated by suture 
from it. Its relations in Chamezleo throw much light on the point, 
and render it highly probable that the cranial prolongation in the 
three groups just mentioned is really continuous with it. As 
pointed out above, the squamosal in Chameleo extends inwards 
to the parietal, forming the greater part of the parieto-quadrate 
* See Essay on Primary Groups of Reptilia Squamata (Proceedings Academy 
of Natural Science, Phila., 1864, p. 230). 
+ See, on Pythonomorpha, Trans. Am. Philos. Soc., 1869, p. 178. 
