128 THE MEDUSAE. 



Browne (: 06) as R. coeruleum Haeckel, as well as with Haeckel's specimens 

 of R. coeruleum from the Canary Islands. It is to be distinguished by its 

 small size (8-10 mm. in diameter), by the form of the gonads, which are 

 cylindrical and occupy only the central third of the radial canals, and by the 

 number of otocysts, which never normally surpasses sixteen. Even this 

 number seems to be reached only in very large individuals, most specimens 

 having only eight. Another character on which Browne has laid stress, and 

 which I find very constant in the present large series is the presence of an 

 apical thickening or "top knot" of the gelatinous disc (PI. 2, fig. 8). This 

 character, although perhaps trivial, sharply distinguishes this species from 

 the ensuing one. Regarding the name to be adopted for this species, it 

 seems to me best to retain R. velcdum. For although adult specimens were 

 first described as R. coeruleum by Haeckel ('79), yet the individuals on which 

 Gegenbaur based his earlier account of R. velatum were sufficiently advanced 

 for specific determination. 



I have no difficulty in identifying the second species with the R. 

 funerarium of Vanhoffen (: 02 b ), from his excellent figures. The"Siboga" 

 specimens recorded by Maas under the name R. coeruleum Haeckel are 

 likewise identical with this form (Maas, : 05, p. 51). This species is dis- 

 tinguished from R. velatum by large size (30 mm. in diameter), long gonads, 

 absence of an apical thickening, greater number (thirty-two) of otocysts, and 

 by the brilliant iridescence of its subumbrella surface. Maas doubts whether 

 this form can be identified with the very unsatisfactory figures given by 

 Quoy et Gaimard of Dianaea funerarium, and therefore includes it in R. 

 coeruleum Haeckel, which he believes resembles it more closely than does 

 any other known species. To this identification Browne (: 0G) objects 

 that the "Siboga" specimens have very long gonads, and entirely lack the 

 apical " top knot," so prominent in Haeckel's figures ('79, taf. 17, fig. 3). 

 Indeed there is little resemblance between the two except the bluish iri- 

 descence; and I believe, as already stated, that 11. coeruleum Haeckel is in 

 reality a synonym of R. velatum. Following this conclusion I shall retain for 

 ihe present species VanholTen's name, JR. funerarium, dating it, however, from 

 Vanhoffen (: 02 1 '), not from Quoy et Gaimard. This seems one of the cases 

 where it is unprofitable to endeavor to identify the specimens in question 

 with any of the older accounts, for, being an intermediate and not a surface 

 form, ii is altogether probable that it had never been observed until taken 

 by the "YaHivia," unless it may he identical with the poorly preserved speci- 



