264 THE VOYAGE OF H.M.S. CHALLENGER. 
relatively to their width, than in Fhizocrinus lofotensis, while the third brachial is oblong 
and not trapezoidal, so that there is no sudden narrowing of the arm at the syzygy 
between the third and fourth brachials. The shape of the arm-joints too, especially of 
those which bear pinnules, is not the same in the two species; while the pinnules them- 
selves, and more particularly those on the proximal parts of the arms, differ very 
considerably in appearance, those of Rhizocrinus rawsoni having broad lower joints. 
The visceral mass of Rhizocrinus lofotensis is relatively lower than that of Rhizocrinus 
rawsoni, in which it is supported by the first six brachials (Pl. X. fig. 20); while in 
Rhizocrinus lofotensis the ambulacra leave the peristome at the level of the second 
brachials, on to which they pass. 
The stem-joints of Rhizocrinus rawsoni are relatively shorter and thicker than those 
of Rhizocrinus lofotensis, in which the length is three times the width, and the radicular 
cirri at the base of the stem are much more numerous in this species than in Rhizocrinus 
rawsom. In fact there are no radicular cirri whatever in one of the Challenger 
specimens of Rhizocrinus rawsoni, and only two, borne upon the first joint above the 
root, in one of those dredged by the ‘‘ Porcupine.” In correspondence with this, the root 
of Rhizocrinus rawsont is more like that of Bathycrinus, the lowest stem-joint giving 
rise to three or more stout branches, which themselves eventually subdivide and bear 
radicular cirri (Pl. X. fig. 15). This condition appears to be comparatively rare in Phizo- 
crinus lofotensis, in which the lowest stem-joint is often provided with from five to nine 
slender cirri, but does not give attachment to a spreading root. 
The longest cup yet known in Rhizocrinus rawsoni was found in some individuals 
which were dredged by the “'Travailleur” in 1882, at a depth of 1900 metres (1000 
fathoms), off Cape Blane, on the coast of Morocco, and were referred by Prof. Perrier 
to a new genus Democrinus.’ The cup is singularly elongated in form, as will be seen 
by comparing the measurements kindly furnished me by Prof. Perrier, with those 
given below for the Challenger, “ Blake,” and “ Porcupine ” specimens. 
Democrinus Parfaiti, Perrier= Rhizocrinus rawsoni, Pourtales. 
Dimensions. 
Length of the calyx from the terminal furrow to the first stem-joint, . 3 9:0 mm. 
Maximum diameter of the calyx, : . : - : 20055 
Height of the radials, : 4 : - 2 : : 0-2 ,, 
Diameter of the stem-joints, . , ‘ : : : : LON 
Length of the stem-joints, . : : : 2:05.55 
The basals of this type thus form a cup 9 mm. high from its lower extremity to the 
constriction at the level of the basiradial suture; while its maximum diameter is not 
more than 2 mm., twice that of the stem-joints. 
1 Comptes rendus, t. xcvi., 1888, p. 450. 
