forms and very different sizes. These various degrees of complica- 

 tion have given rise to numerous divisions *. 

 We will designate by the general name of 



Medusa, 



Or Medusa proper, those which have a true mouth in the middle of 

 the inferior surface, either simply open at the surface or prolonged 

 into a pedicle. 



Under the name of 



^QUOREA, 



We may re-vmite those in which this mouth is simple and not pro- 

 longed, nor furnished with arms. 



When there are no tentacula round the umbella they constitute 

 the Phorcynia of Lamarck f. 



When the circumference of the vimbella is furnished with tentacu- 

 la we have tlie ^quorea proper — ^quorea of Peron — one of the 

 most numerous of all the subgenera, particularly in the seas of hot 

 climates |. 



Certain species are remarkable for having their inferior surface 

 covered with laminae, and others — Foveolia, Peron — for little fos- 

 sulse, which are placed round the circumference of the umbella §. 



We might also unite under the name of 



Pelagia, 



Those in which the mouth is prolonged into a peduncle or is divided 

 into ai-ms ||. 



In all these subgenera there are no lateral cavities, but in a much 

 greater number of these Meduste Avith a siinple mouth, we find, in 

 the thickness of the umbella, four organs formed of a plaited mem- 

 brane, which at certain seasons are filled with an opaque substance, 

 and which appear to be ovaries. They are usually placed in as 

 many cavities opening on the inferior surface, or on the sides of the 

 pedicle, and Avhich have been erroneously (in my opinion) taken for 

 mouths, because little animals are sometimes entangled in them ^. 



* For this geiuis, see the Prodromus of Peron and Lesueur, Ann, du Mns., XIV, 

 and XV ; it is well to remember that their genera are frequently founded on b.id 

 figures, such as those of Baster andBorlasse, and -u-ithout having seen the animals ; 

 and that they have increased the number of species beyond all bounds, 



f The Fhorcini and EuKmenes of Piiron. 



X Medusa aquorea, Gm, ; Forsk., XXXI ; Encyc., Vers, XCV, 1 ; ^quorea meso- 

 nema, Peron; Forsk., XXVIII. B. ; — Med. mucilaginosa, Chamiss,, and Eisenli., 

 Ac. Nat. Cur. X, part I. pi. xxx, f. 2, and the species engraved by M, Lesueur and 

 indicated by Peron, Ann. du Mus., XV, and by M. de Lamarck, Hist., dcs Anim. 

 sans vert., II, 498, et seq. It is to be regretted that these plates are not to be pur- 

 chased. I also add to them the Pegasia, and Melitea of P6rou. 



§ Medusa moUicim, Forsk,, XXXIII, C; Encyc, XCV, 1, 2; — Medusa perht, the 

 genus MjiLiCERTE Peron. 



II Pelayia panopyra, P^ron, Voy. aux Torres Aust., XXXI, 2 ; the Callirhoe 

 and EvAGORA, Per., should also be united to it. 



% This 0[)inion of Baster and Miiller induced Peron to divide a portion of these 

 Medusse into Monostoma and Polvstoma. 



