A FEW CCELENTERATES OF WOODS HOLL. II9 



identity of the genera Gemmaria and Zanclea of McCrady and 

 Gegenbaur I should have to dissent, at least until such time as 

 more convincing evidence than is at present adduced shall be 

 submitted. Reasons for this will be seen in what has been said 

 in the sections dealing with these subjects. It seems desirable, 

 however, to offer a few additional suggestions bearing upon the 

 matter. 



Admitting the doubt expressed by McCrady as to the distinct- 

 ness of his proposed genus, which was only what might have 

 been expected under the circumstances, the fact must not be 

 overlooked that subsequent students of medusae have generally 

 accepted without hesitation the validity of McCrady's genus. A. 

 Agassiz who was quite familiar with the medusae of Gemmaria 

 has described a second species under it, namely, G. cladophora ; 

 and in a comparison of Gemmaria and Zanclea says : " The form 

 of the bell, of the digestive cavity and of the tentacles are totally 

 different in the two genera" (" Cat. N. Am. Acalephae," p. 185). 



Haeckel also has always recognized the distinctness of the two 

 genera, and has himself described a new species under Gemmaria, 

 namely, G. sagittata. He says : " Up to the present time the 

 genus Zanclea has been represented only by a Mediterranean 

 species, Z. costata from Messina. L. Agassiz added to this two 

 other species, Z. ambigna and Z. gemmosa. Of these however, 

 the first is to be placed under Pteronema, the latter under Gem- 

 maria." (" Syst. der Medusen," p. 102.) 



In Hartlaub's revised definition of Zanclea he has naturally 

 enlarged that of Gegenbaur in order to include under it medusae 

 hitherto described under Gemmaria. But in so doing he fails to 

 submit any grounds of sufficient warrant for a measure thus 

 radical. Let it not be overlooked that thus far the ontogeny of 

 Gegenbaur's medusa is wholly unknown. And furthermore, 

 that even the medusa itself has been rarely seen, or certainly 

 identified by later naturalists. 



I do not overlook the circumstance that Browne has described 

 specimens of Gemmaria implexa having four tentacles, which he 

 seems to regard as older specimens of those which when first 

 liberated have but two tentacles. This however is merely an in- 

 ference, for he has not traced these four-tentacled specimens to 



