526 PHILOSOPHICAL TRANSACTIONS. [aNNO I762. 



serves, has been very improperly applied to this kind of animals; for it is certain 

 that not a single species of them is possessed of that stinging quality like a nettle, 

 which the ancients ascribed to them, and that only their ten taenia feel rough and 

 clammy when touched with the finger. Even this roughness is not perceptible, 

 but when the animal attempts to lay hold of the finger : it then throws out of 

 the whole surface of the feeler a number of extremely minute suckers, which 

 sticking fast to the small protuberances of the skin, produce the sensation of a 

 roughness, which is so far from being painful, that it even cannot be called dis- 

 agreeable. 



The genus which these sea-nettles belong to is that of the hydra of Linneus, 

 commonly called the polype. This will appear from the following characters : 

 from the gelatinous substance, of which this whole tribe of animals consists ; from 

 their having only one opening in their bodies, which gives a passage to the food 

 as well as to the excrements of the animal ; and from a set of feelers, which sur- 

 round this opening, and serve for claws to catch their prey and convey it to 

 their mouths. As the sea-nettles agree perfectly in those general characters with 

 the hydra, so do they also answer to many of its less essential, or merely acci- 

 dental qualities: they live for instance constantly in the water, in which they 

 never swim, but always adhere to some fixed body in it; and when they change 

 their place, most of them crawl along so very slowly, that their progressive mo- 

 tions cannot be perceived with the eye. To this may be added, that they like- 

 wise bring forth their young ones alive, and that they grow again after consider- 

 able parts of their bodies have been cut off: all which proves still further, that 

 these animal flowers, or sea-nettles, are of the same nature, have the same 

 characters, and do consequently belong to the same genus with the hydra. The 

 polypes in general may be divided into 2 classes, the one containing those 

 polypes, that cannot conceal their feelers, though ever so much irritated; and 

 the other, those that on the least irritation contract themselves, draw in their 

 feelers, and frequently hide them under a membranaceous cover made for that 

 purpose. The first class, on account of the small number of species belonging 

 to it, needs no subdivisions; but to distinguish properly the several sorts of the 

 2d class, it is necessary to divide it according to the various positions of the feel- 

 ers, which are inserted either in the membranaceous cover itself, or into a flower- 

 like production of the body, or lastly, in the very top part, or the disk of the 

 polype: hence arise the three following subdivisions of the 2d class: 1. Hydra 

 calyciflora. 2. Hydra coroUiflora; and lastly, Hydra disciflora. 



The first class consists but of a single sort, whose specifical character may be 

 thus expressed : 



Hydra tentaculis denudatis, numerosissimis ; corpore longitudinaliter sulcato.* 

 The body of this polype is of a light chestnut colour, and feels perfectly smooth. 



