1898] PENTACRINUS : A NAME AND ITS HISTORY 247 



coarse, and are arranged in petals so broad that they run together 

 towards the centre (figs. VII., X.) and are not distinct as in type B. The 

 cirri are transversely elliptical or circular in section (fig. IIL), and the 

 whorls not so numerous. Infrabasals have only been detected once, 

 and in that instance are quite minute. Basals may or may not form 

 a complete circlet. The radials are not prolonged downwards into 

 spines. The arms fork once or many times, but always equally 



I. 



PENTACRININAE. 



Pentacrimos fossilis, Blumenbach. Portion of stem, cup, and portion of arm 



showing rami, ramules, and pinnules. 

 II. Pentacrinus fossilis. Portion of a cirrus, and articular facet of a cirral. 



III. Isocrinus astevia, Linn. sp. Portion of a cirrus, and articular facet of a cirral. 



IV. Metacrinus niosclcyi, P. H. Carpenter. Cup and proximal portion of an arm. 



After P. H. C. 

 v. Isocrinus jjeiidulus, H. v. Meyer. The cup seen from below, with portion of 

 stem, bearing cirri, still attached, and with proximal brachials. After H. v. 

 Meyer, em P. de Loriol. 

 VI. Isocrinus pemlulus. A radius, showing regular bifurcation of arm. After De 

 Loriol. 

 VII. Isocrinus amblyxcalaris, Thurmann. Closely allied to or identical with I. 



peiululus. Articular facet of an internodal columnal. After De Loriol. 

 VIII. Balanocrinus subteres. Miinster, sp. Articular facet of an internodal, diagram- 

 matised from E 991 in Brit. Mus. Our type A. 

 IX. Pentacrinus fossilis. Articular facet of an internodal, diagrammatised from 



51170 in Brit. Mus. Our type B. 

 X. Isocrinus asteria. Articular facet of an internodal, diagrammatised from E 6456 

 in Brit. Mus. Our type C. 



(fig. VI.). There are two brachials below the first forking (Ax), and 

 these bear no pinnules. D is known only from recent seas, and 

 occurs in the West Pacific. It resembles C, but has 5-8 brachials 

 below the first arm-forking, and of these the 3rd, 4th, 6th and 7th 

 bear pinnules (fig. IV.). The basals form a complete circlet. 



No dispute arises with regard to the names of A and D. De 

 Loriol has perhaps strained a point in extending to A the name of 



