H. James-Clark—The American Spongilla. 433 
The monads are so transparent, and the organization so distinct, 
that the collar and flagellum may be seen clearly from an oppo- 
site point of view, looking directly through the body of the 
halid. This, too, is the best position from which to study 
the contractile vesicles. 
by Plunging the focus half way through a chamber, serves best 
to disclose the manner in which the posterior ends (/) of the 
The body, proper (fig. 8, 7), of a cephalid is a little shorter 
w hape. Its 
? 
The contractile vesicles \v).—The body of the monad is dis- 
ed 
her large, cl y : 
from each other, but always close to the periphery. These clear 
particular place in the body, although they, usually, are not in 
front. The systole and diastole are sr slow, but very 
distinct, if sufficient patience is summoned to wat y 
and without joer epiini The last third of the systole 1s 
