Chap. IV. FAMILY OF PELAGID^. 123 



though the number of lobes remams the same, the tentacular lappets being united 

 with the ocular lappets. The lobes of the adult are, therefore, only partially 

 homologous to the lobes of the young, each lobe being increased, in course of 

 time, by the addition of a lappet from the intervening tentacular lobe. It is true 

 Gegenbaur states that the specimens he has observed had already ovaries and 

 spermaries, with eggs and spermatic cells, but it should not be forgotten that in 

 Aurelia the genital organs are alreadj^ beginning to be developed before the ten- 

 tacles make their appearance (PL XP. Fig. 4). There is, therefore, nothing extra- 

 ordinary in finding, as Gegenbaur has observed, from nine to twelve eggs in one 

 ovary; and fur from satisfying me that this is an evidence of maturity, I would 

 rather infer from the small number of these eggs, that the Medusa? called Nausi- 

 thoe are young animals, since in all mature Discophoraj thus far known, the ninnber 

 of eggs is always enormously large. There is, fLu-ther, something in the figure 

 of Nausithoe published by Gegenbaur, in Cams' Icones Zootomies, PI. II. Fig. 17, 

 which excites my distrust, and to which I take the liberty of calling his attention. 

 In all the Discophora? which I have examined, the angles of the mouth are in 

 the radial prolongation of eyes, and the genital organs alternate with them. In 

 the figure just quoted, on the contrary, the angles of the mouth alternate with 

 ocular pouches, and there are four genital organs in the radial prolongation of 

 the angles of the nxouth, while four others alternate with them. Should this be 

 true to nature, it would be contrary to every thing which I have thus far observed 

 in the symmetrical arrangement of the parts in Discophoroe. I am, therefore, inclined 

 to believe that the cross formed by the angle of the mouth has been incorrectly 

 drawn in the figure of Gegenbaiu', and that it should be turned so that the angles 

 of the mouth should be brought in the radial prolongation of four of the eyes, 

 and alternate with the ovaries. This change in the figure would bring other parts 

 into natural relations which I also believe to be incorrectly represented here. 

 Thfe digitate appendages, x (PI. II. Fig. 17, of Cams' Icones), which, as I have shown 

 in the description of Aurelia, belong to the sexual system, do not appear here 

 to be at all connected with the ovaries, for one set of the ovarian sacs is repre- 

 sented in the radial prolongation of the angles of the mouth, while the other set 

 stands in a somewhat asymmetrical relation to these digitate appendages. But if 

 the cornel's of the mouth Avere brought into the position I have alluded to above, 

 each of the bundles of the digitate appendages {x) would at once assume sym- 

 metrical relations to two ovarian sacs, and if we now go one step further, and 

 compare the figure so altered with either Fig. '1, PI. XII. of my third volume, 

 or PI. XXXIII. Fig. 6 of Wagner's Icones, it will appear that the eight genital sacs 

 of Nausithoe, as figured by Gegenbaur, are homologous to the lobes of the genital 

 pouches, which, in Pelagia, extend towards the peduncles of the actinostome, and, 



