94 BULLETIN OF THE 
Serolis before the formation of the rhabdome proper is rather in favor 
of my interpretation than opposed to it. The direct evidence that the 
axial body is a proximal extension of the cone cells is not as conclusive 
as could be desired. The condition which most favors this view is as 
follows. In longitudinal and transverse sections of the ommatidia, both 
in adult and embryonic specimens, no line of separation has been observed 
between the protoplasm at the deep end of the cone and the substance 
which occupies the axial part of the ommatidium proximal to the cone 
(compare Fig. 65). In attempting to determine the true relation, it is 
important to keep clearly in mind the fact that the proximal end of the 
cone, usually bounded by a sharply marked line, is not the proximal end 
of the cone cells ; but, as Watase (’90, Plate XXIX. Fig. 1) has well shown, 
the cone is surrounded proximally as well as latetally by the protoplasmic 
material of its cells. It is this material, not that of the cone proper, 
which forms the proximal elongation. 
I had hoped that by isolating the elements of the retina I could ob- 
tain more conclusive evidence of the connection of these parts, but my 
efforts were of no avail. My ill success was due, I believe, not to any 
want of connection between the structures treated, but to the fact that 
the material at my disposal had been kept so long in strong alcohol that 
it had become unfit to serve for isolation. This conclusion seems to me 
to be confirmed by the fact that I was unable even to isolate satistac- 
torily the retinul, structures which are usually separable with ease in 
the fresh retinas of most Crustaceans. 
If the view which I have set forth in the foregoing paragraphs con- 
cerning the interpretation to be put upon the axial part of the so called 
rhabdome of Serolis be correct, it follows that the true rhabdome of this 
Crustacean ‘must be considered as composed of four rhabdomeres, each 
of which is applied to the axial face of its appropriate retinular cell, 
and that these four rhabdomes are prevented from uniting with one 
another by a proximal extension of the cone cells which occupies the 
axis of the ommatidium from the cone to the basement membrane. 
Beddard (’84%, p. 21), in his account of the eye in S. Schythei, states 
‘that the cone is “‘ enclosed in a sheath of deep black pigment cells,” and 
Watase (’90, p. 294) has observed that in this genus there are two such 
cells for each ommatidium. I believe that the number has been given 
correctly, for although I have not satisfactorily isolated the cells, I feel 
confident that I have identified their nuclei, and the number of these is 
‘twice that of the ommatidia. 
The nuclei of these pigment cells are most satisfactorily seen in ad- 
