234 THE VOYAGE OF H.M.S. CHALLENGER. 



eight pinnules which contain the short fusiform genital glands show this feature most 

 distinctly. Somewhat the same character presents itself in the enlarged lower portions 

 of the long pinnules of Hyocrinus. But in this case the plate-like sides of the piunule- 

 joints diverge considerably, so that the median groove is widened instead of narrowed as 

 in Bathycrinus. It is therefore partially roofed in by side plates (PI. Vc. figs. 9, 10), 

 of which there is no trace in Bathycrinus. But the plate-like sides of the joints bound a 

 narrow ventral furrow, just as in the arms, and the covering plates rest directly upon 

 their edges (PI. VII. figs. 7, 8 ; PI. VIII. figs. 3, 5), as is the case in Rhizocrinus and in 

 the outer parts of the pinnules of Hyocrinus (PL Vc. fig. 9 ; PL IX. fig. 4 ; PL X. fig. 20). 

 They are continued down the sides of the arm-grooves on to the disk, and in Bathycrinus 

 cddrichianus, which has no orals, they stand up all round the edge of the peristome, as is 

 represented, though badly, in PL VII. fig. 3. These covering plates are scarcely so 

 substantial as the corresponding plates in Hyocrinus, and are also narrower, though nearly 

 as long. 



The two lower brachials and part of the third assist in the protection of the visceral 

 mass, the upper surface of which is more or less strongly convex (PL VII. fig. 3). There 

 is a very large, funnel-shaped peristomial opening, at the bottom of which is the mouth, 

 and the anus is on a low papilla in one of the five interradial areas. In Bathycrinus 

 carpenteri these are supported, according to Danielssen and Koren, by large retiform 

 calcareous plates a little sunk in the perisome, which are obviously persistent orals, 

 though they seem to be entirely absent in the three other species of the genus. In his 

 preliminary description' of Bathycrinus aldrichianus Sii- Wyville Thomson said " the 

 disk is membranous, with scattered calcareous granules. The mouth is subcentral ; there 

 are no regular oral plates ; but there seems to be a determination of calcareous matter to 

 five interradial points round the mouth, v/here it forms little ii-regular calcareous bosses." 

 This description was accompanied by a woodcut which was definitely stated to represent 

 the Bathycrinus from Station lOG (in Mid- Atlantic), and not one of the numerous 

 specimens obtained at Stations 146 and 147 in the Southern Ocean. The whole set were at 

 first regarded by Sir Wyville Thomson as belonging to one and the same species, to which 

 he gave the name Bathycrinus aldrichianus ; but he subsequently limited this name to 

 the individuals from the Southern Ocean. They are figured on PL VII., which was lettered 

 and printed off" before his death. The disk of one of them is shown on PL VII. fig. 3, and 

 obviously bears neither scattered calcareous granules nor interradial bosses round 

 the mouth. This individual has not come into my hands ; but the disk of another which 

 I have examined is perfectly naked, except for the covering-plates at the sides of the 

 ambulacra, and the peristome is like that shown in fig. 3. The specimen which was 

 obtained at Station 106, and had been already figured in the Journal of the Linnean 

 Society as Bathycrinus aldrichianus, was drawn by Mr. Black for PL VIII. ; but on one 

 1 Journ. Linn. Soc. Land. (ZooL), 1876, vol. xiii. pp. 50, 51 ; also in The Atlantic, 1877, vol. ii. pp. 92-95, fig. 23. 



