4 6 



THE HYDROMEDUSAE 



REPRODUCTION. The asexual reproduction of this group is 

 apparently of the usual laminar type : medusoids, nectophores, 



Fifi. 49. 



Fia. 51. 



40. Diagram of Physalia (modified from Cuvier and Haeckel). 



50. Upper surface of Velella, blowing pneumatophore and sail (after Cuvier). 



61. Cormidium of Physalia, with a gonodendron (modified from Haeckel). 



/>, dactylozooid ; G, gastrozooid ; <iP, gonopalpon or dactylozooid on the gonodendrou ; 

 M 9 female medusoid, ultimately freed ; M <j , male sporosac ; PN, pneumatophore ; 2', tentacle 

 (palpacle) of dactylozooid or iilpon. 



and (sometimes) hydrophyllia are formed after the manner sketched 

 on p. 20. The development of the fertilised ovum is known only 



