﻿April, 1857.] 



ELLIOTT SOCIETY. 



171 



can recognize, so far as my acquaintance with that genus goes, as 

 its homologue, being the multifid semi-cartilaginous process, which 

 bears the grand train of digestive, tentaculiform, and sexual indi- 

 viduals. 



The characters of the group, as it at present stands, therefore, 

 may be imperfectly summed up as follows: 



Larva unknown. Individuals living united together in commu- 

 nities, the base of which is a budding Medusa. They are special- 

 ized into classes, performing different functions, and which 

 seem to be mainly these: — 1st, the original or supporting 

 Medusa; 2d, the locomotive individuals or swim-bells; 3d, the 

 digestive individuals; 4th, the tentaculiform individuals; and if 

 we do not unite the bracts w r ith the digestive individuals, we have 

 5th, respiratory individuals, or bracts. The most general charac- 

 teristics of the medusa-bell, when present, are a great thickness 

 and cartilaginous firmness, and a tendency to the formation of pro- 

 cesses from the upper external surface of the disk, (see pi. 8, fig. 

 10, c.) for the more perfect adaptation of the bell to its position in 

 the community: an almost universal absence of color, even in the 

 bell margin — an absence of tentacula, and, in their stead, the 

 occasional presence of sharp triangular processes from the tentacu- 

 lar margin — an absence of ocelli. This absence of color in the medu- 

 sa-bell, when the latter is present,is sometimes compensated by the 

 intense coloration of the digestive trunks and tentaculiform indi- 

 viduals. The latter, also, which are sometimes branched, exhibit 

 an extraordinary development of the thread-cells. 



Of the group of Physophorida3, I know no representatives in 

 our harbor. There are representatives of Diphyidae and Physa- 

 lidae, but the rareness with which they occur makes my knowledge 

 of them very limited. 



I. DIPHYID.E. 



Basal disk highly developed ; often provided with two bell- 

 cavities ; one of which gives exit to the budding modified digest- 

 ive trunk with its appendages, including the single large swim-bell 

 usually present in the genus ; the other acts as a swim-bell. Di- 

 gestive trunk bearing a variable number of appendages of four 

 sorts, swim-bells, bracts, secondary digestive trunks, and tentaculi- 

 form individuals. 



