REPORT ON THE CRINOIDEA. 229 
case in Rhizoerinus, as pointed out by Ludwig ;' but Bathycrinus occupies an inter- 
mediate position between Rhizocrinus and the types just mentioned, for the two 
converging cords within each radial are united by an intraradial commissure just as in 
Pentacrinus and Rhizocrinus (Pl. VIIa. fig. 6; Pl. XXIV. fig. 9—ico). This does not 
appear in the section represented in Pl. VIIb. fig. 4, though it is plainly visible in the 
next one. 
The distribution of the axial cords proceeding from the chambered organ of Bathycrinus 
is thus of a very singular character (woodcuts, figs. 18, 14). Each of the five primary 
Fic. 13.—Diagrammatic vertical section through the Fig. 14.—Plan of the distribution of the 
calyx of Bathycrinus aldrichianus ; x 35. It is inter- axial cords in the calyx of Bathycrinus 
radial on the right side, passing between two of the aldrichianus. B, basals; R1 R2 first 
chambers of the chambered organ, and through the and second radials. 
synostosis of two radials (which is shaded darker) so 
as to show the primary interradial cord (ai); while on 
the left side it passes along the middle line of a ray, 
and shows the axial cord (A) in the distal part of the 
radial (R1). B, ring of anchylosed basals ; ca, fibrillar 
sheath round vascular axis of stem; ch, one of the 
chambers of the quinquelocular organ ; ch’, its down- 
ward extension into the stem ; c.co, interradial portion 
of circular commissure; 7, basiradial ligament; dd, 
dorsal ligament; Ui, interarticular ligament; m, 
muscle; v, central vessel of the stem; x, plexiform 
gland. 
interradial cords proceeds upwards close to the central axis of the basal ring (woodcut, fig. 
13, at). They pass out of this ring just inside the edge of its central funnel, at the inner 
ends of the ridges which separate the fossee lodging the radials and marking the median 
lines of the basals. For the remainder of their course each of them is contained in the 
more or less complete canal which is formed by the apposition of two grooves, one on each 
of two contiguous lateral faces of the radials. These grooves, which run downwards from 
1 Op. cit., Zeitschr. f. wiss. Zool., 1877, Bd. xxix. p. 72. 
‘] ’ ’ ) I 
