Coe and Kunkel— California Limbless Lizard. 393 
dorsal wall of the head, embedded in connective tissue and separated 
from the cranial cavity by a thin, slightly differentiated layer of the 
same. 
With relation to the brain, the pineal eye has a position just dorsal 
to the constriction which marks the boundary between the cerebral 
hemispheres and the olfactory lobes (fig. 51, pi). Because of the 
length of the cerebral hemispheres and the posterior inclination of 
the epiphysis, Anniedla shows a much wider separation between the 
pineal eye and epiphysis than any other lizard. 
In shape, the pineal eye is a much flattened circular vesicle, the 
axis of rotation of which is vertical. The diameter of the vesicle is 
from 0.18 to 0.20™™ and the thickness 0.06 to 0.07™™. 
The blood vessels in the region of the parietal eye show very great 
variation. In some specimens the blood supply is very inconspicuous 
while in others there is a very much distended vessel extending along 
the mid-dorsal line of the brain, from the cheroid plexus of the third 
and fourth ventricles anteriorly to a point just ventral to the pineal 
eye (fig. 50). Here it forms a distinct enlargement and breaks up 
into a number of branches which in general are distributed over the 
surface of the brain in this region, between the cerebral hemispheres 
and the olfactory lobes. A small branch also enters the vacuolated 
tissue surronnding the pineal eye. Just at the point of this vessel’s 
breaking up into its terminal branches, it presses into the pit in a 
semicircle and becomes somewhat enlarged. Notwithstanding its 
similarity in outward appearance to a stalk connecting the pineal eye 
and the epiphysis, sections show conclusively that it is a blood vessel. 
It seems quite possible that some of the parietal nerves shown in 
Spencer’s drawings of the pineal eye of a number of lizards, may 
be nothing but blood vessels, and that in this respect his figures are 
misleading. 
The hollow vesicle, forming the eye, may be differentiated into 
two quite distinct parts, which, however, are perfectly continuous, as 
Francotte (’87) and Béraneck (’87) have shown in the papers already 
mentioned for Anguis, and not discontinuous, as de Graaf (’86) has 
figured them. 
Netina.—As mentioned above, the pineal eye and especially its 
retinal portion, shows a structure very similar to that of the epiphysis. 
The quantity of pigment, however, obscures the details somewhat, so 
that the structure cannot be so certainly ascertained. Externally is 
a single layer of cuboidal cells with rather large nuclei. These cells 
contain less pigment than the inner retinal layers, so that they are 
