1901] MICROSCOPICAL JOURNAL. 317 
very convex» nature, remained in position. In other 
words, it would be impossible for the ephippium to form 
a closed covering for the egg. 
In addition to the outer protective covering which has 
just been described, there are:also some very delicate in- 
ner membranes which surround the egg, as indicated in 
fig. 1, They most probably consist of the moulted inner 
layer of the shell valves, and, so far as can be seen, do 
not appear to have undergone any special alteration. The 
resting egg itself—there is never more than one in any 
ephippium—is very largely composed of small globules 
of a dull greenish oily material. At the edges it is 
slightly translucent, but elsewhere opaque. It can readily 
be distinguished from a ‘‘summer” or parthenogenetic 
ege by its rather larger size and general opacity. Of 
-course it is enclosed in a special covering of its own,’ the 
egg-shell properly so-called. In fig. 3 a broken egg-shell 
is shown, inside its protecting ephippium, after the hatch- 
ing out of the young Bosmina, 
It will be apparent from the foregoing description that 
the ephippium of Bosmina much more nearly approaches 
the homologous structures found in the majority of the 
Lrynceide than it does those of the Daphnide. It is, in 
fact, scarcely worthy of the name of an ephippium, as 
that word is commonly understood, but would be more 
correctly designated as a proto-ephippium, a term I have 
already employed for these less highly developed types 
of protective egg-coverings.—Quekett Club. 
On the Resolution of Amphipleura Pelleucida with a 
Dry Lens and Axial Illumination. 
A. A. MERLIN, F. R. M.S. 
Many members of our Club have been long familiar 
with the structure of Amphipleura pellucida.as revealed 
by oil-immersion objectives of the highest class and aper- 
