482 iiB. 15. T. liUowNB ON [Mar. 17, 



be easily recognized. The other fourteen species of Thaumantias 

 form a miscellaneous group, which, owing to their vague descrip- 

 tions, have caused a considerable amount of trouble to recent 

 writers on MedusEB. 



ITaeckel has divided these species amongst two families — 

 Thaumantidie and Kucopidce — the former cliaracterined by the 

 absence of marginal vesicles, and the latter by the possession of 

 them. Forbes has omitted the vesicles in the descriptions and 

 figures of nearly all his species, and accoi'ding to his views 

 they were worthless for specific characters. If Forbes had only 

 added these important organs to his drawings, which have been 

 rendered almost useless by their omission, the present confusion 

 would never have arisen. It is clear that Forbes has seen the 

 marginal vesicles in some of the species, as in his monograph (p. 9) 

 he writes : — " I have observed the vibration of the otolites 

 distinctly in more than one species of Thaumantias." 



After the publication of Forbes's monograph the name of 

 Thaumantias hemisphcerica appeared on most lists of Medusae, 

 usually without any description of the medusa. 



Since the appearance of Ilaeckel's monograph the name has 

 gone out of fashion, and Phialidium variabile has taken its place. 

 For three years I have searched for Thaumantias hemisphcerica 

 and the allied species, also without marginal vesicles, but without 

 any success. Every specimen, which has the slightest resemblance 

 to one of Forbes's figures, possesses marginal vesicles. 



I may here add that specimens preserved in alcohol are not to 

 be relied upon for the absence of marginal vesicles in the living 

 medusa ; the vesicles often shrivel up and the otohths disappear. 



Laodioe ceuoiata (ForskSl). 



Ilaeckel has placed under the name of Laodiee cruciata no less 

 than twenty-five synonyms, which are divided into two groups — 

 one for the Mediterranean form of Laodiee cruciata, and the other 

 for the Atlantic form. 



The synonyms of the Atlantic form may be divided into two 

 sets, one referring to Medusa cequorea, Baster (1759), the other to 

 Thaxmiantias piloseUa, Forbes (1848). 



Medusa cequorea, Baster (1759); Linnajus (1767). 



Oallirhoe basteriana, Peron and Lesueur (1809); Eschscholtz 

 (1829) ; Blainville (1834). 



The original descriptions and figures of this medusa given by 

 Baster, and copied by other writers, without any additional 

 information, appears to me to be too vague for the purpose of 

 identification. The drawings clearly show that the sub-umbrella 

 has been injured, as the stomach and some of the bands of gonads 

 on the radial canals are in a damaged condition. Whatever kind 

 of medusa Baster had under observation, the description and 

 figures appear to be too vague to identify it with any species 

 known to us at the present day. 



