CHAP. II.] 



MADEIRA TO THE COAST OF BRAZIL. 



Hyocrinus BetheUianus (Fig. 24) is 

 a totally different thing ; and yet from 

 certain points of resemblance one is 

 inclined to regard it in the mean time 

 as an aberrant member of the same 

 group. It has very much the appear- 

 ance, and in some prominent particu- 

 lars it seems to have very much the 

 structure, of the paleozoic genus Pla- 

 tycrinus, or its subgenus Diehocrinus. 



The longest portion of the stem 

 which we dredged was about 170 mm. 

 in length, but the basal part was want- 

 ing, and we had no means of determin- 

 ing what were its means of attachment. 

 The stem is much more rigid than that 

 of Bathyerinus., and is made up of cy- 

 lindrical joints which are united to one 

 another by a close syzygial suture, the 

 applied surfaces being marked with a 

 radiating pattern of grooves and ridges 

 like those of so many of the fossil gen- 

 era, and like those of the recent Pen- 

 tacrinus. The joints become short 

 and very numerous toward the base 

 of the cup. 



The head, including the cup and the 

 arms, is about 60 mm. in length. The 

 cup consists of two tiers of plates only. 

 The lower of these, which must be re- 

 garded as a ring of basals, is formed, 

 as in some of the Platycrinidte, of two 

 or three pieces ; it is difficult to make 

 out which with certainty, for the pieces are more or less united, 



