222 HARGITT. [ VOL. II. 



What I shall have to offer in this paper, therefore, will be 

 upon the other genera named, namely, Coryne, Gonionemus, 

 Hybocodon, Pennaria, Nemopsis, and Margelis. 



Coryne. 



Of specimens of Coryne a comparatively few were avail- 

 able, though they were examined with unusual interest and 

 care as belonging to the genus to which, apparently among 

 the earliest, references to variation among Hydromedusae were 

 made, and which called out the rather remarkable proposition 

 of Bateson quoted in the opening paragraph of this paper. 

 While the specimens were too few to warrant any definite con- 

 clusions, they nevertheless showed a most remarkable con- 

 stancy in every morphological feature, not a single specimen 

 exhibiting the slightest variation in any of the more conspicu- 

 ous features, as tentacles, radial canals, manubrium, etc. If 

 this constancy is as marked in different regions of distribution 

 and for the large numbers cited by Bateson, it is not strange 

 that he should refer to the matter in the terms quoted, as it 

 would seem to be among the least variable of the free-swimming 

 medusae of this group. It will at the same time show how 

 very unsafe must be any such conclusion taken from so limited 

 a range of observation. 



Hybocodon. 



Of the genus Hybocodon Ag. the number of specimens at 

 my command has likewise been somewhat limited, slightly 

 less than two hundred, still they have been sufficient to show 

 some variation in certain features. This genus was insti- 

 tuted by L. Agassiz ('62), under which he included a Hydro- 

 medusa of very unique characters (cf. Contribution to the 

 Natural History of tJic United States, Vol. IV, p. 243), one of 

 which is the proliferous budding of medusae from the hydranth, 

 which in turn give rise to secondary and many later speci- 

 mens by a similar process of budding. (Cf. op. cit., PI. XXV, 

 Fig. 13.) 



The specimens which came into my hands were all preserved 

 in formalin and had in consequence suffered considerable 



