652 ACALKPIIA. 



bably ovaries. Notwitlistanding its very singular shape, this animal may be considered as resembling 

 a Callianira, in winch the wings are excessively developed. 



Tliere is but one known species, C. Venei-is, " the Girdle of Venns," which, considered as a ribbon, is five feet 

 lonL;", and t\\o inches broad ; but as an animal, it is five feet broad, and two inches high. It inhabits the Medi- 

 terranean ; but its substance is so tender, that it is difficult to preserve an entire specimen. 



Tlie two g"enera followiuK", thoufj^h long included anion^ the'MeduscC, ouglit rather to form a small separate family 

 of the order, on account of the interior cartila2;e which supports the g-elatinous substance of their body. 



Porpitti, have a circular cartilage, and the surface marked with concentric stria', crossed by radiating ones. 

 The u|iper surface is simply invested with a thin membrane, which projects beyond it; but the under surface is 

 fnrnished with many tentacula, the external ones long, and beset with small cilia terminating in little globes ; 

 these sometimes contain air; and those toward the middle are the shortest, simplest, and most fleshy. In the 

 niiilille of these trntacula the mouth is situated, in the form of a small projectile proboscis. It leads to a sini[.le 

 sttHiiacli, surrounded by a coat of glandular substance. There is only one known species, which is uf a blai k 

 colour, and found in the jMediterranean and the warmer seas. 



Vijlella, have the mouth and tentacula like the preceding, only the latter are not ciliated. The cartila:ri5 is oval, 

 and has a crest of some elevation passing obliquely across it, and it is transparent, without striae. There is but one 

 known si)ecies, which inhaljits the same seas as Poi-pita. It is fried and eaten. 



THE SECOND ORDER OF THE ACALEPIU. 



THE IIYDROSTATICA. 



The members of this order are distuiu:uishe(l by one or more vessels filled "ivith air, by means 

 of \\lii(di thev keep themselves suspended in the water. Appendages, exceedingly membranous, 

 and varied in their forms, some of them ])robably suckers, and others ovaries, are atraclied to 

 the air ves^^els, and with these constitute the whole visible organization of the animal. 



Physalia, — 



Consists of a large ohlnng air vessel, \\\\\i an oblique and wrinkled salient crest on the ap})cr surface, and 

 funiishcil below, near one of the ends, with a nnmljcr of eylindrical appendages, which have their 

 extremities of diffcmnt forms, but tliey all communicate with the air vessel. The middle ones are 

 beset with groups of little filaments ; and the lateral ones end in two threads eacli, one of ^\hich is 

 usually very long. There is apparently a very small opening at one end uf tlie air vessel ; Init there 

 are no intestines visilde, though there is an inner vessel, with a thinner tunic, from 'a Inch cteua 

 proceed to the processes of the crest ; and no nervous, or circulating, or glandular system is visible. 

 Thfv float u[>on the surface of the seaA\hcii smooth, and the crest answers the purpose of a sail. 

 When living, it has two filaments nnich larger than tlie others, which are gemmed with a sort of pearly- 

 looking drops. AYlien touched it stings or burns the fingers, like those Medusae which are called " sea 

 nettles." They are found in all tlie warm :>eas, and have been, strangely enough, confounded with 

 Hulutliuria. 



Pil VSSOPnORA, — 



Resemble Physaha in their general characters ; but the air vessel is much smaller, has no crest, and is 

 often aceom[ianied liy lateral cnies still t,maller. The tentacula, whudi are very numerous, aie suspended 

 in a bunch under the au" vessels. 



'\'\\t ]*hiissop]tora, properly so called, have the secondary air vessels placed laterally under the principal one ; 

 and the tentacula are conical, cylindriciil, or termiruiting in thread-like appendages, the last being suscei>tible of 

 considerable elongation. 



Uippopus, have only lateral vesicles, semicircular, or resemblins: the foot of a Horse. These are arrans"ed in 

 two ruu's like till' terrains on the spikes of certain grasses; and by their united contraction and dilatation, the 

 atiinial < an movi; witii cunsidtrable velocity. [As the Physalia have been compared to little sailing boats, so these 

 m;iy be looked upon as a sort of steamer in miniature.] CapulUte-, have vesicles attached in two regular rows, 

 oltin of a pretty long axis. Racemida, have the vessels small and globular, and united into an oval mass. 

 Rliizojihiiza, lia\'r a single air vevesel on the top of a stem, on the sides of which the tentacula are attached. 

 S/A'j'I/aiio/ni(i, have the secondary air vessels blended with the tentacula aiound tliu ^tem. 



DlPHYliS, 



Arc curious animals, dill'erent from tlie Hydrostatic Acalepha, and yet, perhaps, resembling them more 

 than any oilier animals in the system. Two of them are always found together, one within the cavity 



