8 M. F. Miiller on the Systematic Position of the Charybdeidse. 



cipated that this would derive support from the developmental 

 history. Still earlier, although information of the fact did not 

 penetrate to the place of my exile until subsequently, E,. Leuckart, 

 following the same idea, had formed the section of Ceratostera, 

 but soon gave it up again; for his supposition has, as is well 

 known, proved to be quite destitute of foundation. Krohn saw 

 Pelngia noctiluca reproduce without change of brood, whilst 

 Busch traced the brood of Chrysaoraj which is scarcely separable 

 generically from Pelagiaj up to the polype-form. Among the 

 Hydroida, it has been shown by Gegenbaur that Trachynema 

 ciliatum, and by myself that Geryonia (Liriope) catharinensis, 

 are probably developed directly from the Q^^; whilst, on the 

 contrary, the supposition of the direct evolution of the JEc/inida, 

 founded solely upon the ciliary coat of the young of jEginopsis, 

 has lost its support by the discovery of ciliated brood in the 

 stomach of Cunina Kollikeri. 



Nevertheless, my formerly imagined grouping of the Disco- 

 phorcB has become more and more plausible with every new in- 

 vestigation. It appears to me that in this case, as in so many 

 others, the unfettered intuition of the older observers has hit 

 the right course in uniting with Charyhdea marsupialis and jt?er2- 

 phylla the Charyhdea hitentaculata, which is now usually placed, 

 under the name of JEginopsis mediterranean J. MiilL, or ^. bi- 

 tentaculata, Koll.*, in the family JEginidae, at the end of 

 the Cryptocarpce. Not that I would support the union of Cha- 

 ryhdea and j^ginopsis in the same genus, or even, after the ex- 

 ample of Liitken, in the same family ; but I am of opinion that 

 the families Charybdeidae and ^ginidse, Gghr.j are to he united 

 to form a group of the Hydromedusse equivalent to the Siphono- 

 phora, Hydroida, «w^ Acalephse (in Leuckart's sense). To group 

 together the most highly organized of all known Hydromedusse, 

 and perhaps of all Coelenterata, the Tamoya quadrumana, and 

 the 2Sginid(Bj which apparently represent the lowest step in the 

 series of Hydromedusse, and some of which, such as Eurystoma, 

 Koll., only digest by the cavity of the lower surface, which is 

 partially closed by the velum t, certainly long appeared to me to be 

 rather a doubtful course. Since I have been able to examine care- 

 fully a species extremely similar to this Eurystoma both in form 



* The diflference of colouring can hardly be accepted as a specific di- 

 stinction in a group of animals in which, as in the Acalephse {Rhizostoma, 

 Chrysaora, &c.) and Hydroida {Corymorpha)^ the greatest variability of 

 coloration within the species may almost be regarded as the rule. 



t I did not think I might doubt this representation of Kolliker's (which 

 is probably erroneous) upon Gegenbaur's authority alone, as in other Me- 

 dus<B I had not always found his statements perfectly well founded, — still 

 less on account of any a-priori notions respecting " a general plan of the 

 Medusae." 



