246 THE VOYAGE OF H.M.8. CHALLENGER. 
The calyx is higher than wide, generally much so. It consists of five basals and 
five radials, of which the former (in the recent species at least) are much the longer. 
Arms five, 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 
support 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 
plates, but no side plates. 
Remarks.—The name Riizocrinus was first employed in 1864 by the late M. Sars? 
to designate a singular new Crinoid which had been discovered by G. O. 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 Sir Wyville Thomson, led to the dredging cruise of H.M.S. “Lightning” in 1868. 
The results of this cruise, Rhizocrinus among them, were so remarkable that it was 
followed by the ‘‘ Porcupine” Expedition of 1869-70, and eventually by the voyage of 
the Challenger. It was 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, Rhizocrinus had been 
rediscovered by the late Count Pourtales during the dredgings carried on by the U.S. 
Coast Survey in connection with the regular exploration of the Gulf Stream.? At that 
time (May 1868) Sars’s elaborate memoir on the type had not yet appeared, and the 
specimens dredged by Pourtales were described by him as ‘ undoubtedly belonging to 
the genus Bourgueticrinus, as defined by d’Orbigny,” a remark in which I entirely 
concur. He gave the provisional specific name “ Hotessiert” to his specimens, thinking 
that they might possibly be identical with Bourgueticrinus Hotessieri, VOxrb., stem-joints 
of which had been discovered in a recent breccia 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 adopted Sars’s name Phizocrinus lofotensis.* 
But he took a totally different 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 Riizocrinus was doubtfully given by Meneghini* to some 
1 Forhandl. Vidensk. Selsk., Christiania, 1864, p. 127. “Den 14de. October, Hr. Sars holdt et Foredrag om 
Pentacrinoide tilstanden af Comatula sarsit og om en ny levende Crinoide Rhizocrinus lofotensis.” 
* Contributions to the Fauna of the Gulf Stream at Great Depths, Bull. Mus. Comp. Zodl., 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 Expedi- 
tions, in 1867, 1868, 1869, Ibid., No. 11, p. 357. 
4 T Crinoidi Terziarii, Atti dell. Soc. Tose. di Sci. Nat., vol. ii. pp. 46, 50. 
