502 CHARLES W. HARGITT 
B. Hydractinia echinata Flem. 
During the summer of 1907 I was fortunate in securing large 
numbers of this hydroid in the height of its breeding season, and 
took occasion to study the development and life history of the 
species. Some account of the life history has already been given 
(08) which obviates any call for emphasis here on this point. 
The early development was studied from living material during 
two summers and at the same time material was carefully pre- 
served for cytological study. This latter was turned over to my 
colleague, Dr. Smallwood, and his results have already appeared 
(09). It only remains for me to submit such accounts of my 
observations as seem important in order to afford a more or less 
complete and connected description of phases of development, 
especially when correlated with Smallwood’s account referred 
to above. 
There are numerous points of difference between my observa- 
tions and those of Bunting (’94), some of which may be due to the 
fact that her studies were restricted to material obtained from the 
small colonies living upon shells occupied by hermit crabs, while 
my material was derived chiefly from colonies of enormous size, 
obtained from piles of docks or similar habitat, but with compari- 
son from the former sorts. As pointed out in the paper referred 
to above (’08, p. 98), there is no adequate reason for regarding 
these hydroids as other than a single species, hence any differ- 
ences to be cited must be incidental rather than fundamental. 
One of the first points of difference to be noted is concerning 
the time at which the liberation of sexual products takes place. 
According to Bunting this is between the hours of 9:30 and 10:30 
p.M. That it occurs during the night I have repeatedly demon- 
strated. Further, that it may occur in certain cases about the 
time stated by Miss Bunting, I have also found true. But that 
it may also occur at a much later hour, and also at varying hours, 
I have also found to be the case. Some of the best cleavage 
series obtained, especially for the very early stages, were in the 
mornings from seven to nine o’clock. That is to say, the eggs 
had been deposited some time after midnight, and at the hours 
