28 THE VOYAGE OF H.M.S. CHALLENGER. 
dual figured by Sars’ they occur on the lowest thirty-three jomts of a stem with fifty- 
nine joints altogether. In another case five out of eighteen joints are cirriferous ; while 
the individual represented in Pl. IX. fig. 1 has only nine cirriferous joints in a stem of 
over forty. A similar variation occurs in Rhizocrinus rawsoni. Every joint in the 
lowest part of the stem may bear cirri at one or both ends of the long axis of its upper 
face. But I have in no case found more than fifteen joints in this condition, and they 
are sometimes not consecutive, a cirrus-less joint being occasionally interposed between 
two others which bear cirri (Pl. X. fig. 15). On the other hand, in the only individual 
with a complete stem which was obtained by the Challenger, and also in the young 
specimens dredged by the “ Porcupine,” there are no radicular cirri at all, but only a 
spreading root formed by subdivision of the main axis of the stem (Pl. LHI. fig. 7) ; and 
this appears to be a constant condition in Bathycrinus (Pl. VIL. figs. 1, 9; Pl. VIIa. 
fig. 3). 
Below the last of the regular and dice-box shaped joints, which may or may not bear 
cirri, there come one or more others of irregular shape and variable size. Spreading 
rootlets proceed outwards from these, as a rule more abundantly in Rhizocrinus than in 
Bathycrinus. In Rhizocrinus lofotensis this inferior joint usually bears several slender 
root filaments disposed around a central one ; while one or two stronger and branching 
rootlets sometimes come off between it and the regular stem-joints. This is more 
especially the case in Rhizocrinus rawsoni ; but in Bathycrinus the inferior joint, or “ root- 
joint” as it has been called, is quite short, and gives off two or rarely three chief roots, 
which themselves subdivide into smaller ones (Pl. VII. figs. 1, 9; Pl. VIIla. fig. 3). 
Both these rootlets of the stem-axis itself and the radicular cirri are composed of a 
series of gradually diminishing joints closely united by ligaments. They attach them- 
selves to foreign bodies by calcareous expansions round their ends or beneath the sides on 
which they happen to rest (Pl. IX. fig. 1; Pl. X. fig. 15). Anything serves for this 
purpose which may improve the anchorage of the Crinoid in the soft mud, which is nearly 
universal at great depths, e.g., fragments of shell, grains of sand, sponge-spicules, foramin- 
iferal tests, &c. Hence, whatever be the case in the Pentacrinide, Rhizocrinus and 
Bathycrinus must remain permanently fixed in one place throughout life. 
In a specimen of Rhizocrinus rawsoni which was dredged by the “ Travailleur,” and 
was described as a new genus Democrinus by Perrier,’ the diameter of the stem is lessened 
at the origin of two groups of rootlets, and regains its former size lower down. Perrier 
suggests the question “si la partie qui se prolonge au dela des racines n’est pas destinée & 
devenir un second pédoncule surmonté d'un second calice. Si cette induction se vérifie, 
les Democrinus constitueront le premier exemple actuel d’Echinodermes vivant en 
1 Op. cit., tab. i. fig. 1. 
2 Sur un nouveau Crinoide fixé, le Democrinus Parfaiti, provenant des dragages du “ Travailleur,” Comptes rendus, 
t. xcvi., No. 7, pp. 450, 451: 
7 ia Om “ee 
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