REPORT ON THE CRINOIDEA. 



229 



case in Rlnzocrinus, as pointed out by Ludwig ; ^ but Bathycrinus occupies an inter- 

 mediate position between RMzocrinus and the types just mentioned, for the two 

 converging cords within each radial are united by an intraradial commissure just as in 

 Pentacnnus and Rhizocrinus (PL Villa, fig. 6; PI. XXIV. fig. 9— fco). This does not 

 appear in the section represented in PI. Vllb. fig. 4, though it is phiinly visible in the 

 next one. 



The distribution of the axial cords proceeding from the chambered organ oi Bathycrinus 

 is thus of a very singular character (woodcuts, figs. 13, 14). Each of the five primary 



Fig. 13. — Diagrammatic vertical section througli the Fio. 14. — Plan of the distribution of the 



c.aly.x oi Bathycrinus aldrichianus ; x 35. It is inter- a.xial cords in the caly.x of Bathycrinus 



radial on the right side, passing between two of the aldrichianus. B, basals ; ijl Ii2 first 



chambers of the chambered organ, and through the and second radials. 



sjTiostosis of two radials (which is shaded darker) so 

 as to show the primary iuterradial cord (ai) ; while on 

 the left side it passes along the middle line of a ray, 

 and shows the axial cord (.-1) in the distal part of the 

 radial (i?'). 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, iuterradial portion 

 of circular commissure ; I, basiradial ligament ; Id, 

 dorsal ligament ; li, interarticular ligament ; m, 

 muscle ; v, central vessel of the stem ; x, plexiform 

 glaud. 



iuterradial cords proceeds upwards close to the central axis of the basal ring (woodcut, fig. 

 13, ai). They pass out of this ring just inside the edge of its central funnel, at the inner 

 ends of the ridges which separate the fossje 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 



^ 0}). cit., Zcitschr.f. wiss. ZooL, 1877, Bd. xxix. p. 72. 



