794 PROF. J. R. GREENE ON A RARE MEDUSA. [Dec. 16, 



the only charybdeid which has been reinvestigated by several 

 observers. In particular Claus has just given us a monograph 

 describing and illustrating, with great minuteness of detail, the form 

 and structure of this common Mediterranean Medusa. His essay 

 may justly rank as the most thorough analysis, hitherto published, 

 of the anatomy of any Medusa whatsoever. 



The affinity here noted was perceived by Fritz Miiller, who at once 

 referred his Medusae to Gegenbaur's Charybdeidce, in the definition 

 of which family he proposed some modifications, to adapt it for the 

 reception of the two species of the new genus Tamoya. The characters 

 of the latter he contrasted with those of Charybdea ( = C. marsupi- 

 alis only) in parallel columns. But writing in 1859, at a distance 

 from Europe, Fritz Miiller needed the data we now possess for such 

 a comparison. Claus, with his better knowledge of the Mediterra- 

 nean species, has shown that the differences on which his predecessor 

 relied do not in fact exist. We cannot estimate as of generic value 

 the characters which separate C. marsupialis from T. haplonema. 

 These Medusae are therefore now placed in one genus {Charybdea 

 of Claus, not Peron and Lesueur). They are very like one another, 

 though both are obviously distinct from the rarer Brazilian species, 

 T. quadrumana, for which the genus founded by Fritz Miiller may 

 still be retained. 



The Brazilian is indeed much larger than the Mediterranean Cha- 

 rybdea, and in this respect resembles one of the unnamed Charyb- 

 deidce (from the Philippine seas) provisionally described and figured 

 in outline by Semper, who doubts the specific identity of any of his 

 own forms with either of those discovered by Fritz Miiller. 



The Charybdeidce are, unquestionably, of the greatest interest to 

 any person wishing to understand the classification of the Hydrozoa. 

 They occupy an intermediate position between the lower and the 

 higher Medusas, although, arbitrarily, they may be placed with the 

 latter. Their (1) external morphology, (2) curiously modified 

 ccelenteric system, (3) genitalia quite distinct from the central region 

 of the bell, with its four accessory cavities for the gastric tentacles, 

 (4) muscular apparatus, and (5), above all, their very distinct nervous 

 ring and wonderfully complicated sensory organs display a number 

 of characters, the study of which must amply reward every earnest 

 student of the lower animals. The whole of this subject, to which, 

 sixteen years ago, I endeavoured to direct attention, is now, at length, 

 admirably presented in the work of Claus. 



No English zoologist has written on the Charybdeidce ; nor, so far 

 as I am aware, has any paper on the Medusae been read before our 

 Society since Edward Forbes, in 1851, made a communication on 

 ^SZquorea. But the study of the Charybdeidce is so important that 

 I have thought it desirable to append to the present note a brief 

 history of the literature of these animals. 



Plancus (1739) was the first to describe and figure one of the 

 Charybdeidce. His "urtica soluta marsupium referens" is the 



