EEPUKT ON THE C'lliNOlDEA. 241 



Bathycrinus aldrlchianus, Wyville Thomson, 1876 (PI. VIJ.; Tl. Vila. figs. 1-21 ; 

 PI. Vllb. ; PI. Villa, figs. 4, 5). 



Batliyci-lumt uhlra-hlaniis, Wyv. Tlioins. (pais), .Juiiiii. Linn. Soc. Loud. (Zool.) (l^l76) 1S78, 

 vol. xiii., pp. 47-51 ; Tlie Atlantic, vol. ii. pp. 'Ji-'d'i, 1877. 



Dimensioi 



is. 



Greatest length of stem (Jiile C. W. T.), ..... i'OU-250 mm. 



Longest stem-joints, ....... 3'50 ,, 



Greatest width of lower joints, . . . . . . 2 -00 „ 



Total length of largest head, , . . . . . . 30-00 ,, 



Height of basal ring, . . . . . . 0'80 „ 



Greatest height of radial funnel, ...... 2-10 ,, 



Greatest diameter of radial funnel, . ..... 4"25 ,, 



Least diameter of radial funnel, ...... 1'50 ,, 



Length of second radial, . . . . . . . 3'00 ,, 



Length of third radial, . . . . . . . 2-75 ,, 



Stem composed of about one hundred joints, of vvliieli the first twenty or twenty-five 

 are wider than high, those immediately beneath the cup being mere circular disks, and 

 slightly wider than the thicker ones on which they rest. The next joints below increase 

 slowly in width and more rapidly iu length. The ends are slightly expanded and the 

 terminal faces oval-oblong in form. Their shorter diameter is occupied by a strong and 

 continuous transverse ridge, the directions of the ridges on the two faces of any joint 

 being nearly at right angles to one another. About the middle of the stem the diameter 

 begins to increase more rapidly, and the ends of the joints appear less expanded while the 

 terminal faces are circular ; and near the Ijase the diameter increases considerably, 

 while the length remains the same or even sliglitly diminishes. The ends of the joints 

 are considerably expanded and their faces oval, with their longer axes occupied by 

 an articular ridge which is interrupted at the opening of the centi'al canal. The stem 

 ends below in a small branching root. 



The basals are closely united into a low, smooth ring, which is scarcely wider above 

 than below, where it is of the same diameter as the thin uppermost stem-joints. On its 

 upper surface rests the funnel-shaped radial pentagon which expands uniformly upwards 

 to its distal edge, so that the calyx has the appearance of being much constricted at the 

 basiradial suture. The surface of each radial is strongly convex in the middle but falls 

 away at the sides, so that the rim of the funnel is drawn out into five curved edges in 

 which the second radials rest. These are trapezoidal in form and convex at their 

 proximal ends. This convexity is continued onwards as a ridge of tolerably uniform 

 width, so that there is a flattened surface on either side of it, which increases in size 

 towards the distal edge. This feature is continued on to the axillarics, which are wider 

 than the second radials, and barely pentagonal iu form. The medio-dcrsal ridge enlarges 



(zool. ch.vltj. f.xp. — I'ART XXXII. — 1884.) Ii 31 



