148 
; that it is similar to the mammalian type in its early stages, but the later 
stages are arrested, and in the adult the typical lens cells have degen- 
erated to a form as above described. 
The finer histological structures and relations of the different cells will 
be presented in a later paper. 
The function of such an eye as this may be reasonably conceived when 
we consider the composition and shape of the lens, the almost closed lids 
and the closely crowded condition of the retina. The power of sight 
would doubtless extend little if any beyond the ability of distinguishing 
between light and darkness. 
EXPLANATION OF FIGURES. 
All the figures are semi-diagrammatie camera drawings of sections 
from the mole eye. 
ABBREVIATIONS. 
a. Aqueous chamber. 
b. Blood vessel. 
ce. Cornea. 
cl. Cleft between eyelids. 
i. n. Inner nuclear layer. ‘ 
on. Outer nuclear layer. 
n. ¢ Nuclear or ganglion cell layer. 
]. Lens. 
ll. Lower eyelid. 
ul. Upper eyelid. 
r. b. Retinal blood vessel. 
p. Pigment layer. 
vy. Vitreous chamber. 
scl. Sclerotie coat. 
n. op. Optic nerve. 
l.c. Lens cells. 
Fig. 1.—Vertical section through eye and lids showing the cleft be- 
tween the lids. The section did not pass through the center of the eye. 
x48. 
Fig. 2.—Vertical section passing through center of nerve and lens. The 
thickness of the different layers is correctly represented, but the cells are 
diagrammatic. x48, 
