REPORT ON THE CRINOIDEA. 281 



"Porcupine" and C-hallenger species, Sir WyvUle named them Fentacrinus wyville-ihomsoni 

 and Pentacrinus maclearanus ; and the plate which was drawn under his supervision 

 was lettered Pentacrinus asteria (PI. XL). 



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 Pentacrinidse 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-Medusce of Miller and Mitller, 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.^ 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 "Porcupin-e" 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 (PI. XIX. figs. 6, 7 ; PI. XX. figs. 1-3). Quenstedt^ was unable to 

 see any essential difference between Cainocrinus and Pentaerinus ; 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 Isocrinus, which has been 

 discussed above [ante, p. 271). Cainocrinus was regarded by de Loriol as establishing 

 a transition between Millericrinus and Pentacnnus. He defines Pentacnnus as difier- 



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. 



* Monographie Paleontologique et Gi5o!ogique des iltages Superieurs de la formation Jurassique des Environs de 

 Boulogne-sur-Mer, S""" partie, p. 297. 

 5 Swiss Crinoids, p. 111. 

 " Notice sur les Crinoldes suisses, Bull. Soc. d. Sci. Nat. de Neuchatel, vol. i. p. 213. 



(ZOOL. CHALL. EXP. — PART XXXII. 1884.) li 3G 



