CHARACTERISTIC DEEP-SEA TYPES. BRYOZOA. 



81 



is one of the most common of the West Indian bryozoans inside 

 the two-hundred-fathom line, but extending to nearly 500 fath- 



Fig. 831. — Tessadroma boreale. ^. 



Fig-. 331 a. — Tessadroma bo- 

 reale. Magnified. (Sinitt.) 



cms. Equally common is Tessadroma bo- 

 reale (Figs. 331, 331 a), a species not in- 

 frequent on the east side of the Atlantic 

 from Spitzbergen to the Azores. 



A very common incrusting type found 

 grooving on shells and corals is Hippothoa 

 biaperta (Figs. 332, 332 a), which goes 

 back to the tertiary. 



A species of Cellepora is very abundant 



N 



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w 



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Fig. 382 o. — Hippothoa 

 biaperta. Greatly magni- 

 fied. (Smitt.) 



Fig. 332. — Hippothoa bia-- 

 perta. \ . 



