CHARACTERISTIC DEEP-SEA TYPES. ORINOIDS. 



123 



Hyocrinus, and Ilycrinus ; but the " Blake " was not fortunate 

 enough to obtain any of these. 



The last and perhaps most interesting of the West Indian 

 stalked crinoids belongs to the genus Holopus. (Figs. 413, 414.) 

 Less than half a dozen specimens of it are known to exist. The 

 first specimen collected is now in the museum of the Ecole des 



Fig. 413. — Adult Holopus Rangi. 

 (Carpenter.) 



1 • 



Fig. 414. — Half-giown Holopus Rangi. 

 |. (Carpenter.) 



Mines. Sir Rawson W. Rawson, when Governor of Barbados, 

 obtained three specimens, which were lent to Sir Wyville Thom- 

 son, and have, with the material of the " Blake," formed the 

 basis of Dr. Carpenter's work on the subject. 



The genus Holopus was established by D'Orbigny, in 1837, 

 from a single specimen which was brought from Martinique by 

 Sander Rang. Its true nature was not recognized by other 

 palaeontologists, some of whom considered it to be a barnacle. 

 The dried specimens all have a blackish green tinge ; the single 

 arm dredged off Montserrat had a whitish tint. The arms of 

 all the specimens are strongly curved, closing the disk entirely ; 

 but of course this is not the natural attitude of the animal. 

 Holopus is attached by an irregularly expanded base, formed by 

 the extension of the tubular calyx, which is slightly bent, while 

 a constriction separates the cup from the spreading base. The 

 youngest specimen (Fig. 415), of jet-black color, dredged off 

 Bahia Honda, only 3 mm. in diameter, differs very much from 

 the older specimens, as will be seen from the figures. The 



