REPORT ON THE CRINOIDEA. 241 
Bathycrinus aldrichianus, Wyville Thomson, 1876 (Pl. VIL; Pl. Vila. figs. 1-21; 
fae Vili: Sun Wailer few ea): 
Bathycrinus aldrichianus, Wyv. Thoms. (pars), Journ. Linn. Soc. Lond. (Zool.) (1876) 1878, 
vol. xiii, pp. 47-51; The Atlantic, vol. ii. pp. 92-95, 1877. 
Dimensions. 
Greatest length of stem (fide C. W. T.), . : ‘ : » 200-250 mm. 
Longest stem-joints, : : , ; : : : 3°50 ,, 
Greatest width of lower joints, : 4 ‘ F : : 200m 
Total length of largest head, ‘ 6 ; : : : 30°00 _,, 
Height of basal ring, A , ‘ ‘ 3 s 2 0:80) =; 
Greatest height of radial funnel, . ; : : : : 2A 
Greatest diameter of radial funnel, . : ; : ‘ } 4°25 
Least diameter of radial funnel, —. : : ; ; ; L540) 
Length of second radial, . ; j : : : : BHA) 5 
Length of third radial, } : : : : : : TDs, 
Stem composed of about one hundred joints, of which 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 in 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 base the diameter increases considerably, 
while the length remains the same or even slightly 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 central 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 axillaries, which are wider 
than the second radials, and barely pentagonal in form. The medio-dorsal ridge enlarges 
(z00L, CHALL, EXP,—PART XxXx11.—1884.) li 31 
