394 Coe and Kunkel— Catifornia Limbless Lizard. 
frequently very distinct, forming an outside wall to the vesicle. As 
far as could be made out through the pigment, in the polar region 
there is a single layer of rather tall columnar cells with nuclei situ- 
ated in the basal portions of the cells; in the equatorial region, 
however, where the wall of the vesicle is somewhat thicker than 
elsewhere, the increased thickness 1s due to an intermediate layer of 
cuboidal cells between the outermost layer and the columnar cells. 
This middle layer is rather irregular, but the presence of pigment 
interferes considerably with the accurate determination of the struc- 
ture. The pineal eye of Anniella (pl. xtvur) and Anguis, accord- 
ing to the beautiful photomicrographs of Francotte (’88), show 
striking similarity. Francotte describes three layers of cells in the 
retina of Anguis as follows: 1, an outer layer of cuboidal cells 
forming the external wall ; 2, a layer of spherical cells on which the 
rods rest ; and 3, a layer of fusiform, ciliated rods lining the vesicle. 
In the specimens at hand there was so much pigment present that 
the second layer could not be distinguished except in the equatorial 
region. Francotte’s figures of Angwis show the retina almost free 
from pigment, there being only a little at the inner ends of the 
columnar cells next the cavity, so that the three layers are very 
clearly shown. Because of the general similarity in other respects 
of these closely related forms, Anguis and Anniella, this may be the 
structure of the specimens examined, but so obscured as not to be 
determinable. The columnar cells are not ciliated, although in 
nearly every case a coagulum, in the form of a network having the 
appearance of cilia, is found in the cavity ventrally in contact with 
the retina. 
Differing from Anguis, the pineal eye of Anniella exhibits a 
marked thickening of its wall in the equatorial region. In some 
cases the wall is twice as thick here as in the ventral portion of the 
vesicle. 
The pigment is present in the retina as fine granules of fairly 
uniform size, packed together to form irregular masses. In general 
it is concentrated principally along the lateral cell walls. In the cells 
of the lower pole it is more abundant than in the equatorial region 
and occupies practically the entire thickness of the retinal wall with 
the exception of the outermost layer of cells, and even here some 
pigment is often found. The equatorial region of the vesicle con- 
tains less pigment than the rest of the retina, and it is confined 
principally to the middle part of the columnar cells. In a ring sur- 
rounding the lens there is a large quantity of pigment, forming 
quite a distinct frame for the lens. 
