urn 



ue 



HYDKOZOA 



63 





- 



re: 



rein 



'• F 



■'a: 

 il 1 



obe 



be 



al b 



imin 

 and 



tic of: 



ans 



dbe: 



r rea& 



bu 

 tber I 



\ tf 



'. 







:r, a 



eree 



arty 



'Dr. 



Vledv 



Fig. 13. 



Development of Tttkris : — a, ovum of the medusiform zooid (b) 



known 



developed therefrom. (All magnified.) 



Certain medusiform gonophores, and, it may 

 be also, some true Medusids, possess the power of 

 producing, by gemmation, free-swimming forms 

 which directly resemble themselves. Such buds 

 have been observed to start from the sides of the 

 polypite in Sarsia gemmifera and Lizzia octo- 

 pwnctata, from the reproductive region of the 

 calycine canals in two species of Thaumantias, 

 from the bases of the tentacles in Steenstrupia 

 Owenu and Sarsia prolifera, and from the de- 

 pendent portion of the tentacles themselves in 

 Diplonema {fig. H ). Hence these medusoids 

 ought, perhaps, to be regarded as free gonoblas- 

 tidia. _ Here, also, it may be added, that multi- 

 plication by fission has been observed by Kolliker 

 m a species of Stomobrachium. 



