'I'll University of California Publications in Zoology. [Vol.6 



of the tentacle (fig. 9). A layer of mesogloea forms as in the 

 ease of the distal tentacles, though somewhat later in the develop- 

 ment. 



Gonosome. After the formation of the hydranth cavity, and 

 while the proximal tentacles are little more than conical eleva- 

 tions the gonosome begins to develop as a circlet of rounded 



Fig. ..- -Section through early stage in development of distal tentacle. 



Fij;. 8. — Longitudinal section through outer edge of base of proximal 

 tentai le ; see fig. 4. 



Fig. 9. — Longitudinal section through early proximal tentacle, somewhat 

 oblique; see fig. 4. 



protuberances immediately distal to the latter and. like them, one 

 to a canal, developing only between the ridges of the inter- 

 canalicular tissue (fig. 10). These are the beginnings of the 

 peduncles which hear the medusae. Their number from the 

 beginning equals the number characteristic of adults with sinus 

 of a similar size, and is not increased as development proceeds. 

 In tins respect they differ from the tentacles, the difference being 

 correlated with a more rapid growth in their diameter. For the 

 number of peduncles to appear is conditioned by the diameter 

 af the stem, as in the case of tin- proximal tentacles. This is well 



