38 GENUS FIROLOIDA^ 



genus Firola, to which they approach by the form of their 

 body, their habit, their manners, and by being inhabitants 

 of the same temperate chmates. 



The anatomical characters are very similar to those 

 of that genus, but the simple examination of their figures 

 will exhibit obvious distinctive traits. These differences 

 consist, in the position of the nucleus, the heart, and the 

 branchia. In the Firolas, these organs are placed in a 

 cavity at the base of the tail, by which they are protected 

 from all danger; but in the beings under consideration, 

 they are situated at the posterior extremity of the body; 

 very slightly attached; exposed to every danger; and con- 

 stantly liable to be separated, in consequence of their un- 

 guarded position. 



These differences are, I believe, sufficiently great, to 

 authorize the establishing of a new genus, for the recep- 

 tion of the three new species, which arc here described; 

 possessing, as they do, a common form of body, and simi- 

 larity of habits, but at the same time presenting distinct 

 specific characters, by which, on examination, we shall be 

 able readily to recognize them. 



For this genus, I propose the name of Firoloida 

 under the following characters : 



Genus FIROLOIDA. 



Generic Characters, 



Tentacula none; jaws horny; eyes two; one fin, placed 



on the back; branchia grouped with the heart, around 



an oblong nucleus, situated at the posterior and terminal 



part of the body; tail none. 



Body gelatinous, cyhndrical, glabrous, very similar to 

 that of the Firolae; like them they have a proboscis, two 



