100 THE OCEANIC HYDROZOA. 



founded upon personal observation of the animals in their living state, they might very 

 advisably (if their distinctive characters are really well founded) be taken as the starting 

 point by future observers. I therefore subjoin his definitions. 



1. Physalia caravella. 



The first species is Fhysalia caravella, especially distinguished, according to 

 Eschscholz, by the fact that the polypites arise from a common stem. There is a considerable 

 number of tentacles of equal size, and the polypites and tentacles are all crowded together at 

 one end of the hydrosoma, which is obtuse, in such a manner that the rest of the organ, 

 which is naked, and produced into a proboscidiform process, is almost twice as long as 

 the part provided with polypites. 



When the hydrosoma is so placed that its naked end is anterior, the left side is 

 nearly straight ; the right side, on the other hand, widens towards the middle, and behind 

 this is strongly concave. The series of polypites begins here, and continues to the 

 posterior very blunt end ; at a corresponding point the crest is cmarginate, and it terminates 

 at both ends of the hydrosoma, in specimens where this measures eight inches, at one inch from 

 the end. The colour is bright purplish red, with dark extremities, and blue lines in the 

 folds of the crest. The polypites are violet, with whitish points ; the larger tentacles are red 

 with dark purple acetabula; the smaller tentacles blue: the bundles of buds are reddish. 



This species attains a length of eight inches, and a width of two and a half inches 

 and inhabits the Atlantic from the Azores to the Brazilian coast. 



2. Physalia pelagica. 



The polypites arise singly, and one of the tentacula is often much larger than the others. 

 That end of the body which bears the polypites, S:c., has no fleshy process, but is filled 

 to its point with air. The hinder end of the body is bent towards the right side, while 

 the appendages are attached to the left side on a median prominence. The naked end 

 of the hydrosoma is not separated by any marked excavation from the rest ; and 

 is a third or a fourth part as long as the whole. The crest begins as a slight elevation 

 in the neighbourhood of the anterior naked end, gradually increases in height posteriorly, 

 and ceases suddenly, opposite the root of that posterior process which bears the appendages. 



In young individuals, the hydrosoma is only pale blue. In the adult, both ends are 

 green, and the crest appears to be purple in its highest part. The tentacles are blue, 

 with dark acetabula. In the older individuals, besides the large tentacle, there is a second, 

 smaller one, distinguishable from the rest. The polypites are dark blue, with yellow points. 

 Between the posterior process and the middle part of the hydrosoma, there is a naked 

 spot, where the series of appendages is interrupted. This species attains a length of two and 

 a half inches, and inhabits the Atlantic, especially about the Cape of Good Hope. 



