30 The American Naturalist. [January, 
down to the slight extent that is possible to the animal. The 
covering is of the most delicate texture but strong enough to 
hold firmly together in all the movements ofits possessor. In 
the older parts the cuticle is somewhat more opaque and is 
more or less stuck up with dirt and such things. 
The gonozoids are budded in clusters from the sides of the 
stem near its centre, they have an investment of cuticle which 
eutirely covers them, and the bell develops to its time of release 
but not to its maturity in this case, and can then be seen to 
break off from the parent stock and swim away for itself. The 
stages in the development of the bell are as usual in this order. 
They are as follows. It appears as a minute bud on one side of 
the stalk, and not for some time can it be seen whether it is to 
give rise to a medusa or toa polyp. An enlargement into a 
somewhat spherical head usually indicates the medusoid char- 
acter of the bud. This process is quite gradual as may be seen 
from the figs. 4,5 and 6, all of which, while somewhat diagram- 
matic, were sketched directly from living or preserved and 
mounted specimens. As has been said, they follow the general 
course of development common to the order. Cf. Lang, Comp. 
Anat., p. 105, et seq. 
The first differential change that occurs is a thickening of 
the peripheral ectoderm at the extremity of the bud, with an 
accompanying invagination extending to the entoderm; fig. 
4. This continues as shown in figs: 7 and 8. In this process 
there occurs what may be designated as a cleavage of the ecto- 
derm of the outer margin of the bud, and which extends for 
some distance around the bell, fig. 8. The outer portion consti- 
tates the outer ectodermal envelopes of the medusa, and is 
ruptured and finally atrophies at, or immediately before, the 
