270 
Transactions of the 
TMonthly M'croscopical 
L Journal, May 1,1869. 
rod apparently runs across the zoosperm ; the tail is attached to the 
space between the origins of the rays ; it consists of a single stem, 
which soon divides into three or four branches ; it is of a softer 
material than the rays, being more gelatinous in appearance, and 
having almost the same refracting power as the fluid in which it is 
examined. When the head is viewed slightly within focus on the 
side, a dark line is visible running from the centre towards the apex, 
a little on one side; the top view of the zoosperms shows their 
contour to be circular ; in this position a dark spot is to be seen, 
not always central, surrounded by a bright line, which again is 
bounded by the dark line forming the circumference of the head ; 
from this the three rays project equidistant. When on this view 
it is within focus, the centre spot is bright, instead of being dark. 
I am inclined to think that the rays correspond to the rod of zoo- 
sperm of ^S'. Longirostris, their firmer character pointing to their 
affinity to this, rather than to the softer circumferential rays, which 
more resemble the tail of P. Ber7ihardus in the transparent, fine, 
and gelatinous nature of their appearance. 
Professor Kolliker,* in his paper " On the Universal Formation 
of Zoosperms in Cells," gives a figure of the zoosperms of P. Bern- 
hardus, in which the tail is represented as a long vesicular appen- 
dage forked at the end, and the whole zoosperm finally without 
rays, which are supposed to drop off in course of development. I 
have every reason to believe that this appearance is due to the 
addition of water. 
(Fig. 4a and h). In the Lobster {Homarus vulgaris) the zoo- 
sperms have the same number of parts as in P. Bernhardus ; the 
caput or head is here drawn out into a cylinder, which appears to 
have solid and firm walls, and to contain a substance of less con- 
sistence, but still solid; this substance leaves at one end a small 
cavity, projecting from which and filling up its mouth, is an 
irregular heap of granules, which seems to represent the tail of 
zoosperms in P. Bernhardus ; between the walls of the cavity and 
the base of the heap of granules arise three rays, extremely long 
and flexible, ranging from 1^ to 2^ times the length of the cylin- 
der ; the transverse section of this body is circular, and the contents 
appear to be granular; the length of the cylinder is O'CIS'""', its 
breadth being 0 • 004'"'". 
Leydigt thinks it probable that this kind of zoosperm under- 
goes a further development in the spermatheca of the female : on 
this question I cannot give a decided opinion, as I only examined 
one female specimen, a S. Longirostris, which had been some time 
in spirits of wine ; the zoosperms in the spermatheca of this speci- 
men certainly showed no signs of higher development, there being 
* * Nouveaux Memoires, Societe Helvetique.' Bd. 8. Fig. 37". Taf. 3. 
t ' Lehrbuch der Histologie,' S. 535. 
