\ 
1881.] The Siphonophores. IgI 
organs of the jelly fish, called Lizzia, one species of which, L. octo- 
punctata, is found in the waters of our bays. The helmet-shaped 
organ of the larva of ; 
Agalma will be seen to 
represent the bell of 
the Lizzia,and the egg 
from which it has de- 
veloped the proboscis. S ow 
The central tube of pS. “fe el/s 
the helmet of the \\ SS 
young Aga/ma is the 
exact reproduction of 
the early condition of 
four tubes in the bell 
through which the nourishment of the Lizzia circulates, and 
which are called chymiferous vessels. Tentacles or structures 
corresponding with these thread-like organs, which arise from the 
margin of the bell of a Lizzia, do not in fact exist depending from 
the rim of the helmet-like cap of the primitive larva. 
The primitive larva or Lizzia stage of the young Aga/ma is well 
formed at the end of the fourth day after the eggs have left the 
female bells. Its change into the following or Athorybia stage is 
very rapid, and in outward appearance very radical. Before con- 
sidering the details of these changes let me give names to the 
different parts of the primitive medusa, or Lizzia stage, in order to 
simplify references in the following pages. 
The helmet-shaped bell, fitting over the egg from which it was 
formed, bears very many resemblances to a covering scale, and 
under that name it has generally been described. To avoid con- 
fusion, I suggest for it the name of primitive covering scale, the 
meaning of which designation is, I think, self-evident. The tube- 
like cavity in its center may be known as the primitive tube and 
the cavity in the eggs itself, from which this tube is differentiated, 
as the primitive cavity. That part of the larva which corresponds 
to the proboscis is designated the primitive proboscis. 
Fic. 8.—Primitive larva of Aga/ma. 
The Lizzia stage of the young Agalma is followed by a second, _ 
which from its resemblance to a genus of Siphonophores, called 
Athorybia, I have called after Claus, the Athorybia larva, or 
Athorybia stage of Aga/ma. About the same time that the primi- 
tive medusa stage is reached, there appears as a bud from the 
primitive tube a small structure, which later develops into a float. 
