EXPLANATION OF PLATE XXXVII. 



FIGURE 275. Zygodactyla Grcrnlandica, (p. 729;) profile view, one-half natural size, 

 276. Bougainvillia supereiliuris, (p. 7:V,S ;) a branch, much enlarged. 

 277. Penuaria 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 



(gonothecae,) 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 wero copied from A. Agassiz ; 270 and i*81 from L. Agassi/. ; 278 from J. Lcidy ; 

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



