REPOET ON THE CEINOIDEA. 



23i 



of the copies of tlais plate which were sent to me I found the MS. name Bathycrinus 

 camjihellianus in Sir Wyville's handwriting. He had evidently therefore come to regard 

 this individual as specifically distinct from those subsequently obtained in the Southern 

 Ocean, to which he eventually limited the name Bathycrinus aldrichianus ; and the disk 

 of this individual {Bathycrinus Campbell iamis) corresponds in most respects with his 

 description quoted above. 



The whole of each interradial area is covered with closely set, calcareous plates, not 

 scattered granules ; but I cannot make out that they are more abundant in the immediate 

 neighbourhood of the mouth than elsewhere. The covering plates of the ambulacra are 

 smaller and less regular than in Bathycrinus aldrichianus, and their course can only be 

 followed with difficulty. In the solitary young specimen of Bathycrinus gracilis 

 (PL Villa, fig. 1) there are neither orals nor anambulacral plates, so that in these 

 respects it resembles the southern Bathycrinus aldrichianus rather than the northern 

 Bathycrinus carpenteri. 



In order that I might be able to compare the anatomy of Bathycrinus with that of 

 Rhizocrinus, two of the least perfect examples were cut into thin sections with a Leyser's 

 microtome. Unfortunately, however, the circum-oral portions of the one used for the 

 vertical sections were somewhat mutilated, and the remainder was found to be contracted, 

 and, as it were, coagulated by the action of the spirit, so that not even its general anatomy 

 could be made out, much less any histological detail. The arms, on the other hand, 

 yielded more satisfactory results. 



In correspondence with the different size of the basals, the chambered organ (PL Vllb. 

 figs. 1,2, ch) is more flattened than that of Rhizocrinus. It is continued below into the vas- 

 cular axis of the stem, which is thrown into numerous folds as it passes through the closely 

 packed discoidal joints at the top of the stem. As in Rhizocrinus there is only one central 

 vessel (PL Vila. fig. 2; PL Vllb. fig. 2 — v), and not two or more as in some species of 

 Pentacrinus and in the Comatulse. The plexiform gland rising from the chambered organ 

 expands considerably within the central funnel of the calyx (PL Vllb. figs. 1, 3-5, x), and 

 soon becomes lobulate. It appears to be made up of numerous small cells, which can be 

 traced downwards into the flattened epithelial lining of the vessels in its lower part, and in 

 the chambers of the chambered organ. But it has nothing like the glandular appearance 

 of the corresponding organ in Antedon carinata, the numerous lobules of which consist 

 of distinct tubules lined by columnar cells, like those of the urinary tubules. 



On its way up through the disk the plexiform gland becomes narrower again, probably 

 on account of its giving off extensions which form the intervisceral vessels, as in other 

 Crinoids. It is interradial in position, as usual, and may be followed at the sides of the 

 fore-gut both in transverse and in longitudinal section (PL Vllb. figs. 6-8, x) to a little 

 way below the peristome, where its further course cannot be traced. I have little doubt, 

 however, that its connections are essentially the same as in other Crinoids. But owing to 



