MUSEUM OF COMPARATIVE ZOOLOGY. 61 
indication of ossification of the scleral cartilage, as is common in bony 
fishes, has been seen. No trace of an argentea is to be found. All the 
pigment is of the same dark brown granular variety, and, when seen 
by reflected light, never gives the white, silvery color that is character- 
istic of the crystalline material of the argentea. 
The choroid is exceedingly rudimentary, and in many specimens I 
have been unable to detect its presence at all. In the eye from which 
Figure 13 was drawn (Fig. 13, chr.), —a specimen the eyes of which, as 
will be seen further on, are better developed in several respects than is 
usual in these eyes, — it is more distinctly seen than in any other case 
that I have studied. Here the layer of pigment is very thin; it is in- 
terrupted at short intervals, and cannot be traced for more than one 
third of the distance through which it would normally extend.. Whether 
this pigment should be regarded as representing the lamina supracho- 
roidea, or as belonging to the choroid proper, it is impossible to say. 
In a few instances (Figs. 13, 14, 15, chr. cpl.), a layer of cellular tissue 
has been found at the proximal pole of the eye, extending for a variable 
distance toward the anterior rim of the optic cup, but rarely reaching it. 
This layer is always:closely applied to the outer surface of the pigmented 
layer of the retina, and in some sections it seems to be continuous with 
the pigment of the choroid. In some places (Fig. 15, chr. cpl.) the tissue 
has very much the nature of formed connective tissue, while in other 
places (Figs. 13 and 14, chr. cpl.) the cells are spherical or elliptical, with 
indications at times of blunt processes, and with distinct nuclei, Where 
cells of this kind occur, the layer is somewhat thicker than where the 
structure is more characteristically that of connective tissue ; and in 
several instances blood corpuscles (Fig. 13, cp. sng.) are found scattered 
here and there in these thicker portions of the layer, indicating the 
presence of capillaries, I identify this layer as the chorio-capillaris. 
A conspicuous structure in all the specimens studied is a thick, 
usually short, somewhat lenticular mass of pigment occupying a position 
usually at the proximal pole of the eye, at or near the entrance of the 
optic nerve, by which it is pierced in some cases. (Figs. 14, 15, etc., 
gl. chr.). This mass is concentric with the surface of the retina, but is 
always separated from it by a short though somewhat variable interval. 
In some places the cellular layer just described in part occupies this 
space, and in some places the thin layer of choroid pigment is seen to 
enter the same space. The mass always lies within the sclerotic, and 
is always composed entirely of pigment. I have been unable to find 
any cellular or other protoplasmic elements in it. This body I interpret 
