60 JOHNS HOPKINS UNIVERSITY MORPHOLOGICAL MONOGRAPHS. 
describes what he supposes to be muscle fibers just exterior (distal) 
to the lens, and believes that a contraction of these fibers would 
have the effect of forcing the lens nearer the retina, or vice 
versa. His supposition, like mine, needs experimental verification. 
Hitherto the only instance known of accommodation in the eyes of 
invertebrates was that described by Beer” for Cephalopods. 
The Proximal Complex Eye.—With four exceptions, the description 
and discussion given for the distal complex eye also holds good for 
the proximal complex eye (Fig. 18). The four exceptions are: the 
absence of a capsule to the lens; the absence of the long pigment 
cells; the absence of the pyramid cells; and the different relative 
position of the lens and retina. This eye, then, has a cornea 
continuous with the epithelium of the sensory club, a lens, in 
structure and probable origin quite like that described for the distal 
complex eye, and a retina of prism cells with axial fibers for the 
prisms. Since Conant*® has described this eye quite fully, and 
discussed Schewiakoff’s conclusions at length, I shall be brief. 
Suffice it to say, that Schewiakoff describes two kinds of cells 
(supporting cells and spindle-shaped visual cells) for the retina of 
this eye just as he described for the distal complex eye. The 
vitreous body he likewise describes as being homogeneous and with 
spaces for the visual rods (fibers) of the visual cells. It is evident 
that Schewiakoff has interpreted the structure of this eye from 
analogy with his results on the distal complex eye. Claus likewise 
has described two kinds of cells for the retina, and the vitreous 
body as homogeneous. Conant and myself find only one kind of 
cells in the retina of this eye. The pigmentation that Schewiakoff 
describes for the vitreous body I believe to have been dissolved in 
from the pigmented zone of the retina, for I find no regular 
pigmentation in the vitreous body. Haake’s observation, previously 
noted (p. 42), applies also to the proximal complex eye. 
Conant’s evidence for the axial fibers of the prisms was clearly 
insufficient, so that he did not in this respect complete his Fig. 69. 
I republish this figure with the prism fibers drawn (Fig. 18). 
Since the long pigment cells are absent my reasons for supposing 
the lens of this eye to be adjustable vanish. 
Finally, a word on the origin of the lens and the relative 
position of the lens and retina. The lens and retina in this eye 
