CHAP. IX.J 



THE DEEP-SEA FAUNA. 



455 



representatives of this group, until now supposed 

 to be on the verge of extinction, and that all the 

 known species are from depths beyond the limit 

 of ordinary dredging, we are led to anticipate that 

 crinoids may probably form rather an important 

 element in the abyssal fauna. 



Fig. 74. — Arehaster bifrotis, Wyvtlle Thomson. Oral aspect. Tliiee-fourths the natural size. 



(No. 57, 1869. ) 



The general distribution of the deep sea Asteridea 

 has already been referred to. Perhaps the most 

 obvious peculiarity which they present is the great 

 preponderance of the genera Astrogoniutn, Arehaster, 

 Astropecten, and their allies. Genera belonging 

 to other groups do not apparently become less 



