'24 BRITISH HYDROID ZOOPHYTES. 



Modification and atrophy of "select" 

 bud. Beginning with the " select " polypite, 

 that is to say, with the individual which 

 displays the first step in the series of 

 phenomena connected with reproduction. In 

 the lower division (ATHECATA or naked 

 polypites) some members which bear the 

 gonophores are not modified at all, but in 

 many species the tentacles become more or 

 less aborted and the polypite stunted, and 

 when the higher division (THECAPHORA or 

 sheathed polypites) is reached the " select " 

 polypites do not obtain nourishment from 

 external sources, in fact, they have no mouths 

 and are wholly unrecognizable as polypites. 



There is, however, one exception in this 

 division, amongst our British species, and that 

 exception is the Genus HALECIUM, Oken, where 

 the " select " polypites are fully developed, in 

 other cases they are represented by a mere 

 stump ("Blastostyle") bearing the reproductive 

 buds In THECAPHORA, that which repre- 

 sents the "select" polypite is provided with a 

 receptacle, fairly strong and modified to the 

 special circumstances of the case. This modi- 

 fied receptacle is more in the nature of a case 



