EXPLANATION OF PLATE XXXVII. 



FIGURE 075. Zygodactyla Grceulandica, (p. 729;) profile view, one-half natural size, 

 276. Bougainvillia superciliaris, (p. 733 ;) a branch, much enlarged. 

 277. Pennaria tiarella, (p. 735 ;) a branch, natural size. 

 278. The same ; one of the hydroids, with medusa}, buds developing at the 



base of the proboscis. 

 279. Sertularia pumila, (p. 732 ;) part of a colony on a frond of sea- weed 



natural size. 

 280. Sertularia argentea, (p. 732 ;) a branch bearing reproductive capsules 



(gonothec,) with the soft parts removed, much enlarged. 

 281. Obelia commissuralis, (p. 728;) a branch bearing hydroids and one 



female gonotheca, much enlarged. 



(Figures 275 and 279 were copied from A. Agassiz ; 276 and 281 from L. Agassiz ; 278 from J. Leidy ; 

 77 and 230 were drawn by A. E. Verrill.) 



