CHAP. II.] MADEIRA TO THE COAST OF BRAZIL. 91 



delinitely shaped valves, slightly cupped above, and marked 

 beneath with impressions for the insertion of muscles. The 

 anal opening is on a short plated interradial tube. The mouth 

 opens into a short slightly constricted esophagus, which is suc- 

 ceeded by a dilatation surrounded by brown glandular ridges ; 

 the intestine is very short, and contracts rapidly to a small 

 diameter. Round the esophagus a somewhat ill-defined vascu- 

 lar ring, which may possibly be continuous with the body-cav- 

 ity, gives off opposite each of the oral plates a group of four 

 tubular tentacles. The ovaries are very long, extending nearly 

 the whole length of the first two or three pairs of pinnules on 



Fig. 26.— Disk of Hyocrinus Bethellianus. Eight times the natural size. 



each arm. The assemblage of characters connected with the 

 disk and soft parts shows a considerable resemblance between 

 Hijocrinus and Hhizocrinus. My strong impression is that 

 the mode of nutrition of the Cyathocrinidoe, and consequently 

 the structure and arrangement of their disk, was essentially dif- 

 ferent from that of all the yet known living forms; and I think 

 it is probable that when we have an opportunity of studying 

 the structure of HyocriniLS minutely, we shall find that its very 



