210 ME. P. H. CAEPENTEE ON THE GENTTS SOLANOCEINTJS 



XVI. — The same may be said of the " Solanocrinus JaegerV of 

 Goldfuss, which is nothing but the calyx of a Pentacrinus detached 

 from its stem. This will be evident from a comparison of figs. 23 & 

 24 on PL XI. The three figures 24, a, b, & c, are reproductions 

 of Goldfuss's figures of S. Jaegeri ; while figs. 23, a, b, c, which Dr. 

 Carpenter has kindly permitted me to publish, represent the corre- 

 sponding parts of Pentacrinus Wyville-Thomsoni, dredged by 

 H.M.S. ' Porcupine ' in 800 fms. off the coast of Portugal in 1870. 

 This species has a complete basal circlet, as also have P. Mulleri, 

 Liitken*, and P. Maclearanus of the ' Challenger ' dredgings. On 

 our present classification both of these should be referred to 

 Cainocrinus. This genus was established by Edward Forbes f 

 for the reception of a small form from the London Clay, which 

 resembles the well-known P. briareus and. P. asteria (PI. XI. 

 fig. 21) in all essential points except the possession of a com- 

 plete basal circlet. The distinction has been retained and made 

 more precise by de LoriolJ, probably in ignorance of the exis- 

 tence of two recent species of Cainocrinus. He defines Penta- 

 crinus as differing from Millericrinus in having very small basals, 

 which do not meet externally, and in the verticillar arrangement 

 of the cirrhi. On the other hand, Cainocrinus has a complete 

 ring of basals like Millericrinus, but a stem with verticils of 

 cirrhi like Pentacrinus. I cannot, however, regard this classifi- 

 cation as satisfactory ; for even in those species of Pentacrinus 

 which have an incomplete basal ring there is a great amount of 

 variation in the extent to which the central ends of the basals 

 are joined, and in the size of their outer ends which appear be- 

 tween the radials and the top stem-joint. The basals are 

 least developed in P. asteria (PI. XI. fig. 21), but there are all 

 sorts of gradation between this condition and that of P. Wyville- 

 Thomsoni and of the fossil Cainocrinus. A closed basal circlet 

 occurs in the fossil P. Signiaringensis, Quenstedt§, referred by 

 de Loriol to Cainocrinus, in P. pentagonalis ferratus\\, and in the 

 unnamed specimen^ from Solzenhausen, in which Quenstedt 

 specially describes a closed basal circlet. He does not see any 

 essential difference between Cainocrinus and Pentacrinus, and 



* " Om Vestindiens Pentacriner," Videnskabelige Meddelelser fra den Natur- 

 historiske Forening i Kj'obenhavn, 1864, tab. iv., r. 

 t British Tertiary Echinoderms, p. 33. 



J Swiss Fossil Orinoids, pp. Ill, 112. § Bncriniden, tab. 99. fig. 132. 



|| Ibid. tab. 98. fig. 135. % Ibid. p. 263, tab. 99. fig. 174. 



