4 8 



THE HYDROMEDUSAE 



FIG. 55. Limnocnida from the oral surface (after Gunther). 



manubrium and shallowness of the gastric cavity, it strangely resembles 



many Cuninae, and in bud- 

 ding from the manubrium, 

 it approaches the Antho- 

 medusae. No hydroid stage 

 has been observed in its life- 

 history. 



Limnocodium, on the 

 other hand, resembles more 

 closely Leptomedusae and 

 Trachomedusae (Figs. 52, 

 53). Its generative organs, of 

 which the male only have 

 been observed, are placed on 

 the radial canals, as in both 

 these orders ; but it has a 

 hydroid stage, a thing not 

 known in any Tracho- 

 Fio. 55a.-Diagram of the gemmation of the medu- m edusan, known not to 

 sold of Limnocodium. a, external ectoderm ; 6, endo- . ' 



derm of the radial canals ; c, coelenteron of the hydroid ; OCCUr in many Trachome- 

 d, cavity of radial canal ; e, ectoderm of manubrium ; ,] aT1( ] nj.nl-.qV.lv nnivprqal 

 /, rudiment of subumbral cavity ; g, cavity of maim- c 3cle > dl W1 J l 



brium ; h, endoderm of manubrium, with blind canals ainoi)" Leptomedusae ' 

 (j) ; i, k, ectoderm of eutocodon. (After Fowler.) ,, ? !-,.,<. ^p 



bell and tentacles suggest Trachomedusan affinities. 



