57 
capsule is now solely represented by the chitinous secretion of its 
original wall. 
Each sporosac (female) produces a single ovum in which the ger- 
minal vesicle and spot are distinctly visible. The segmentation of the 
vitellus can be easily followed ; and as the segments become smaller 
and more numerous, a nucleus may be distinguished in each. The 
ovum at the same time increases in size, and the manubrium of the 
sporosac becomes more or less displaced. After the disappearance 
of the mulberry-like condition, an external dermal layer becomes 
distinctly differentiated. It is composed of elongated cells placed 
perpendicularly to the surface, and may be seen to enclose a minutely 
granular mass. The ovum, at the same time, becomes considerably 
elongated, and may be soon seen doubled on itself. It now acquires 
cilia on its surface, and is ready to escape as a free embryo from the 
sporosac, which accordingly becomes ruptured to allow of the exit of 
the embryo, which ultimately gains its final freedom through the 
summit of the capsule. The embryo now moves freely, by the aid of 
its ciliated surface, through the surrounding water. It is of a coni- 
cal or pyriform figure, but very contracted and mutable. Its in- 
terior may be seen to be hollowed out into a cavity, but as yet no 
mouth can be demonstrated. 
I have not yet succeeded in witnessing the change of the loco- 
motive to the fixed state of the polype, but it is doubtless similar 
to what has been observed in the allied forms. 
The male capsules and sporosacs resemble the female so closely 
as only to be distinguishable from them by an examination of the 
contents of the sacs. These contents consist of a mass of sperma- 
togenous tissue, which replaces the single ovum of the female. 
The spermatozoon consist of caudate corpuscles, about 5^0 0 °f an 
inch in diameter. 
Laomedea fiexuosa is strictly dioecious, the male and female go- 
nophores always occurring on separate colonies. 
Antennularia antennina. 
The gonophores in Antennularia antennina are borne upon the 
upper side of the short processes which, springing in verticels from 
the main stem, give support to the polypiferous ramuli. 
VOL. IV. 
H 
