216 THE VOYAGE OF H.M.S. CHALLENGER. 
ance of the more wedge-shaped brachials of a Holopus-arm (PI. IIL. figs. 10-12), but differ 
in having the pinnule-socket at the base of the lateral process instead of on its upper edge. 
Before the discovery of the support below the radials de Loriol considered Hudesi- 
erimus to be a species of Hugentacrinus ; and he still regards it as a member of the family 
Eugeniacrinidz, to which he has also thought of transferring Cotylecrinus, though he 
has never actually done so. This is partly due to his having been led to regard the 
calyx-tube of Holopus and Cyathidiwm as possibly composed of the five basal pieces 
only,’ though there are very serious objections to this view. We know also that the 
Eugeniacrinide, 1.e., Hugeniacrinus, Phyllocrinus, and Tetracrinus, have a jointed stem, 
which is not the case either in Hudesicrinus or in Cotylecrinus. Both these genera seem 
to me to find their proper place in the family Holopidee, which I should characterise as 
follows—Basals and radials closely united into a more or less tubular calyx of variable 
depth. It is sessile and attached by a somewhat spreading base, the foundation of which 
is probably formed by a dorsocentral plate, like that of Marsupites. Ten simple arms, 
composed of a small number of massive joints. 
A. Radials high but asymmetrical, exhibiting a difference of bivium and trivium. 
a. Radials fused together with basals into a tubular body-chamber lodging the viscera. 
A syzygy between the two outer radials, : ; : : - 1. Holopus. 
8. Visceral mass was probably lodged above the radials, which are mostly found 
separated from the subjacent basals and the spreading base of attachment, 
A muscular joint between the two outer radials, : 5 : . 2. Eudesicrinus. 
B, Radials apparently all alike. Two or more calyces sometimes associated as if budding, 
a. Radials and basals fused into a tubular body-chamber, . Z * . 3. Cyathidium. 
B. Radials low, and readily separated from the basals and disk of attachment, . 4. Cotylecrinus. 
The remarkable Jurassic fossil, described by de Loriol as Gymnocrinus,® is still too 
imperfectly known to be placed in this family; but I cannot help suspecting that it is 
only a portion of the cup of a larger Crinoid. On the other hand, Micropocrinus 
gastaldv, described by Michelin® from the Miocene of Superga near Turin, seems to be 
closely allied to Holopus. Michelin’s diagnosis runs as follows: “Radix expansa, non 
ramosa, adhaerens, sublzevis ; corpus breve crassum, rotundatum, subpentagonale, exterius 
granulosum, interius profundum, irregulariter vacuum; margine revoluto in decem 
segmentis acutis subdiviso.” I am somewhat puzzled as to the identity of the ten 
marginal segments. I do not think that they can represent the individual muscle-plates, 
of which there would be ten in a decalcified calyx; nor does it seem likely that 
Micropocrinus is a ten-rayed type like Promachocrinus (ante, pp. 37, 38). The real 
nature of this Crinoid must therefore remain undecided for the present. 
On the other hand, the Paleozoic Edriocrinus, which has been described by Hall 
1 Paléont. Frang., loc. cit., p. 191. 2 Tlid., p. 209. 
$ Description @’un nouveau genre de la Famille de Crinoides, Rev. et Mag. Zool., ser. 2, t. iii. p. 93. 
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