CHARYBDEA. 15 



suppose, with Hfieckel ('80), that they are primitive Scyphomedusae ; on the 

 contrary, there are some grounds for concluding, with Hickson (: 06), that 

 they really represent precocious Scyphistomata, such as the Lucernarida, 

 which have secondarily acquired the free swimming habit. But to come to 

 any sound conclusion on this point, it is absolutely necessary to have fresh 

 material. Further speculation based on Haeckel's ('80) description and 

 figures seems not only unprofitable but misleading. 



For these reasons it seems best to modify the scheme proposed by Maas 

 (: 07), as follows, and to refrain from assigning to the various orders of the 

 class any serial phylogenetic relationships : — 



Order 1. Charybdeida, a very aberrant group. 



Order 2. Stauromedusae (Lucernarida and Tesserida). 



Order 3. Coronata. 



Order 4. Discophora (Saemaeostomata and Rhizostomata). 



Charybdeida. 

 Charybdeidae Gegenbaur. 



Charybdea Peron et Lesueur, 1809. 



The ten species which have been described under this genus differ so 

 slightly one from another, and that only by characters of whose systematic 

 importance different opinions may reasonably be held, that it is difficult to 

 pass judgment on their validity. Maas ('97) has already expressed a doubt 

 as to whether all the species enumerated by Haeckel ('80) are really distinct, 

 suggesting that we may, at least in part, be dealing with geographic races, 

 a conclusion supported by the fact that a different species has been described 

 for almost every locality from which the genus has been recorded. But, on 

 the other hand, tliese races, even if they be nothing more, often seem to be 

 constant, as is the case for C. marsiipialis from the Mediterranean ; while 

 enough specimens of C.xai/machana have now been examined by Conant ('98) 

 and by myself to suggest that this form is also well founded. 



We must bear in mind, in deciding what characters and differences are 

 best fitted to serve as the bases for specific distinctions, that Charybdea should 

 be judged from a different standpoint from Pelagia, or the trachyline 

 Hydromedusae. Although Charybdea and Pelagia, if viewed merely from 

 the descriptive standpoint, seem to show a close parallel in that in both 

 genera numei'ous closely allied species or races have been described from 



