246 THE VOYAGE OF H.M.S. CHALLENGEr>. 



The cal} X i« higher than wide, geuerally much su. It consists of five Ixisals and 

 five radials, of which the former (in the recent species at least) are much the hmger. 

 Arms fi'S'e, the joints united in pairs by syzygies, with pinnules on the epizygals only. 

 The first pinnule on the epizygal of the third or fourth pair. The epizygal of the first 

 pair has the sides of its ventral furrow produced upwards into strong processes which 

 stipport the disk. The peristome is protected by five oral plates of variable size, but the 

 remaining portions of the interpalmar areas are not plated. The ambulacra have covering 

 j^lates, but no side plates. 



Remarha. — The name lihizoci'iiius WixsHrst employed in 1864 by the late M. Sars ^ 

 to designate a singular new Crinoid which had been discovered by G. 0. Sars in his 

 dredgings among the Lofoten Islands ; and it was the extreme interest of this type as 

 a sort of degraded Apiocrinite which, through the intervention of Dr. Carpenter and the 

 late Sii' Wyville Thomson, led to the di'edging cruise of H.M.S. "Lightning" in 1868. 

 The results of this cruise, Rhizocrinns among them, were so remarkable that it was 

 followed l:)y the "Porcupine" Expedition of 1869-70, and eventually by the voyage of 

 the Challenger. It Avas the discovery of Rhizocrinus, therefore, and the interesting- 

 speculations to which this discovery gave rise, that led this country to take a foremost 

 place in the work of deep-sea exploration. Meanwhile, however, Rhizocfiuits had been 

 rediscovered by the late Count Pourtales during the ch-edgings carried on by the U.S. 

 Coast Survey in connection with the regular exploration of the GJulf Stream.'-^ At that 

 time (May 1868) Sars's elaborate memoir on the tyjjc had not yet appeared, and tlie 

 specimens dredged by Pourtales were described by him as " undoubtedly belonging to 

 the genus Bowgueticrimis, as defined by d'Orbigny," a remark in which I entirely 

 concur. He gave the provisional specific name " Hotessieri" to his specimens, thinking 

 that they might possibly be identical with Bourguetio'lnus Hotessieri, d'Orb., stem-joints 

 of which had been discovered in a recent Ijreccia at Guadeloupe. After the appearance 

 of Sars's memoir, however, he recognised the identity of the Gulf Stream and of the 

 Lofoten examples of the type, for which he adoj)ted Sars's name Rkizocrinus lc>f'otensis.' 



But he took a totally diflerent view of the composition of the cup from that proposed 

 by Sars, and in this respect, as will be pointed out immediately, he was decidedly in the 

 right. For the large subradial portion of the summit, which was considered by Sars 

 as an enlarged upper stem-joint, was shown by Pourtales to consist of five closely 

 anchylosed basals. 



In the year 1875 the name Rhizocrinus was doubtfully given by Meneghini^ to some 



1 Forhandl. Vidensl: Selsk., Chiistiauia, 1864, p. 127. "Den UJe. Octuber, Hr. Sar.s lioklt et Foiedrag om 

 Piiiitacrinoide tilstanden af Comatula mrsii og mu eu uy levendu Crinoide Bhkocrinus lofotcnsis." 



- Contributions to the Fauna of the Gulf Stream at Great Depths, Hull. Mus. Comp. ZooL, vol. i., No. 7, p. 128. 



" List of the Crinoids obtained on the coasts of Florida and Cuba by the U.S. Coast Survey Gulf Stream E.xpedi- 

 tions, in 1867, 1868, 1869, Ihid., Ko. 11, p. 357. 



■* I Crinoidi Terziarii, Atti dell. Soc. Tosc. di Sd. Nat., vol. ii. \>f. 46, 50. 



