REPORT ON THE CRINOIDEA. 281 
“Porcupine” and Challenger species, Sir Wyville named them Pentacrinus wyville-thomsoni 
and Pentacrinus maclearanus; and the plate which was drawn under his supervision 
was lettered Pentacrinus asteria (Pl. X1.). 
We may therefore feel tolerably certain that Sir Wyville had recognised the inex- 
pediency of limiting the name Pentacrinus to the Liassic species only, though their 
generic differences from the recent Pentacrinidee had been noticed by him. 
We have seen that the name Cenocrinus, which was applied by Sir Wyville in 1864 
to the classical species Pentacrinus caput-Meduse of Miller and Miiller, was afterwards 
dropped by him; but I cannot make out whether or not this arose from his becoming 
acquainted with the genus Cainocrinus which had been established twelve years pre- 
viously by Forbes.1 The essential difference between this type and Pentacrinus, as 
defined by Forbes, is that the pelvis or basal ring of Pentacrinus is “ composed of a single 
piece formed out of five anchylosed plates,” while that of Cainocrinus is ‘‘ formed out 
of five free plates.” These are seen in Forbes’s figure to compose a closed basal ring which 
separates the radials from the top stem-joint; and this is not the case with the basals 
either of Extracrinus or of Pentacrinus asterius, the only recent species known to 
Forbes. 
What Sir Wyville thought of Forbes’s genus I cannot say. He never referred to it, 
and the fact of his having himself proposed Cenocrinus as a subgeneric type looks rather 
as if he had not been previously acquainted with Cainocrinus. In any case, however, 
whether he knew it or not, he still referred to the same genus Pentacrinus, the species 
which was dredged by the “ Porcupine” in 1870, and was named after himself by his 
colleague Dr. Gwyn Jeffreys,’ F.R.S. ; and this is in all respects a true Cainocrinus with 
a closed basal ring (Pl. XIX. figs..6, 7; Pl XX. figs. 1-3). Quenstedt*® was unable to 
see any essential difference between Cainocrinus and Pentacrinus; but de Loriol,* writing 
about the same time, took a different view. Unaware of Forbes’s genus, he proposed 
to establish a new genus Picteticrinus for a fossil species of Pentacrinus presenting the 
then unusual character of a closed basal ring. But he subsequently discovered this to be 
a feature of the type described by Forbes as Cainocrinus, which he adopted as a generic 
name instead of Picteticrinus ;° and he referred to this type a species that had been 
originally supposed by Desor® to belong to von Meyer's genus Tsocrinus, which has been 
discussed above (ante, p. 271). Cainocrinus was regarded by de Loriol as establishing 
a transition between Millericrinus and Pentacrinus. He defines Pentacrinus as differ- 
1 Monograph of the Echinodermata of the British Tertiaries, pp. 33, 34. 
2 Proc. Roy. Soc. Edin., vol. vii., 1872, p. 767 ; and also The Depths of the Sea, p. 444. 
3 Encriniden, p. 269. 
4 Monographie Paléontologique et Géologique des Kitages Supérieurs de la formation J urassique des Environs de 
Boulogne-sur-Mer, 2™° partie, p. 297. 
5 Swiss Crinoids, p. 111. 
® Notice sur les Crinoides suisses, Bull. Soc. d. Sci. Nat. de Neuchatel, vol. i. p. 213. 
(ZOOL. CHALL. EXP.—PART Xxxi.—1884,) li 36 
