EXPLANATION OF PLATE XXXVII. 



Figure 275. — Zygodactyla Grwulaadica, (p. 729 ;) profile view, oue-lialf uatural size. 

 276. — Bougaiuvillia superciliaris, (p. 733;) a brancli, much enlarged. 

 277. — Pennaria tiarella, (p. 73.5;) a branch, natural size. 

 278. — The same; one of the hydroids, with medusae, 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, 



(gonotheca?, ) 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; 27C and 281 from L. Agaesiz ; 278 from J. Leidy; 

 7 and 280 were drawn by A. E. Verrill.) 



