CHARACTERISTIC DEEP-SEA TYPES. HYDRO-CORALLIN^E. 139 



(Fig. 444.) It has also been found by the." Porcupine " expedi- 

 tion at from 500 to 000 fathoms, in the cold area to the north- 

 ward of the British Islands. 



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Fig. 444. Pliobothrus symmetricus. }. (Pourtal&s.) 



The other family of the group added to the West Indian 

 fauna by deep-sea dredgings is that of the Stylasteridae ; in 

 some of the genera the simple circular digestive opening is 

 drawn out into elongate chambers, while in some genera a 



Fig. 445. f Fig. 445 a. {. 



Cryptohelia Peircei. (Pourtal&s. ) 



tongue-like process or a lid covers in part or wholly this 

 opening. Such an expansion of one edge of the calycle to 

 form a lip (Fig. 445), folded over the opening, we find in 

 Cryptohelia Peircei. (Fig. 445 .) 



Among the most beautiful and delicate of the milleporian 

 corals found on rocky bottom is Stylaster filoyranus (Fig. 



