HYDROSTATICA. 483 



are attached to these vesicles and compose the whole apparent organisation of 

 these animals. They have no apparent mouth, at least none which can be 

 decidedly considered as such. 



PHYSALIA, Lamarck. 



The Physaliae resemble an extremely large oblong bladder, elevated superiorly 

 into an oblique and wrinkled crest, and furnished beneath, near one of its 

 extremities, with numerous, cylindrical, fleshy productions, variously termi- 

 nated, that communicate with the bladder. Those in the middle give origin 

 to more or less numerous groups of little filaments; the lateral ones are 

 merely divided into two threads, one of which is frequently very long. There 

 appears to be an extremely small orifice in one of the extremities of the 

 bladder, but internally no other intestine is found, but another bladder with 

 thinner parietes, and caeca that partly extend into the cavities of the crest. 

 There is no nervous, circulating, nor glandular system. The animal swims 

 on the surface of the sea when it is calm, employing its crest as a tail. When 

 living, it is also furnished with extremely long filaments, more slender than 

 the others, which are sprinkled, as it were, with pearls or drops. Its touch is 

 said to sting and burn like that of the sea-nettle. 



They are found in all the seas of hot climates. 



PHYSSOPHORA, Forskahl. 



These Acalepha are evidently allied to the Physaliae, but their bladder is 

 proportionally much smaller, has no crest, and is frequently accompanied by 

 lateral bladders; their various and numerous tentacula are suspended verti- 

 cally under the bladder, like a garland or cluster. In 



PHYSSOPHORA, Peron, 



Or Physsophora properly so called, between the superior bladder and the ten- 

 tacula are other bladders placed side by side, or one on another, sometimes of 

 an irregular figure, and sometimes polyedrous, forming, by their union, prisms 

 or cylinders. The tentacula, partly conical, partly cylindrical, and partly 

 formed by groups of threads or globules, and finally, partly filiform and sus- 

 ceptible of considerable elongation, form a cluster or garland at the inferior 

 extremity. 



HIPPOPUS, Quoy and Gaymard, 



Where there are merely lateral vesicles, almost semicircular, or shaped like the 

 foot of a horse, and crowded into two ranges, thus forming a sort of spike, 

 comparable to that of certain grasses, from which also depends a kind of gar- 

 land that crosses all the preceding parts. The united contraction of these 

 vesicles enable the animal to move rapidly. 



It is directly after these hydrostatic Acalepha that we may place the 



DIPHYES, Cuvier. 



A very singular genus, where two different individuals are always found 

 together, one encased in a cavity of the other, but susceptible of being sepa- 



i i '2 



