68 THE VOYAGE OF H.M.S. CHALLENGER. 



Genus 2. Atelecrinus, P. H. Carpenter, 1881. 



1869. Antedon, Pourtales (pars), Bull. Mus. Comp. Zobl., 1869, vol. i. No. 11, p. 356. 

 1878. Antedon, Pourtales {pars), Bull. Mus. Comp. Zobl., 1878, vol. v. No. 9, p. 214. 



1881. Atelecrinus, P. H. Carpenter, Bull. Mus. Cornp. Zobl., 1881, vol. ix. No. 4, p. 16. 



1882. Atelecrinus, P. H. Carpenter, Journ. Linn. Soc. Lond. (Zool.), 1882, vol. xvi. p. 488. 



Definition. — Centro-dorsal acorn-shaped, and bearing five vertical double rows of 

 cirrus-sockets, those of each row alternating with one another, and with those of adjoining 

 rows. They have horseshoe-shaped rims, the arches of which are directed upwards 

 while the two ends slant downwards and outwards. Radials separated from the centro- 

 dorsal by a complete circlet of basals. The first six or more brachials bear no pinnules. 



Remarks. — The first example of this genus which was actually obtained was dredged 

 by Pourtales 1 in 1869 off Cojima on the coast of Cuba. Two small ten-armed Comatulae 

 were brought up from a depth of 450 fathoms, and were briefly described by Pourtales 

 under the name of Antedon cubensis. But the description given by him only applies to 

 the larger and more perfect specimen, which differs considerably from the smaller and 

 much mutilated one. He seems to have recognised that the two were different, for in 

 his description 2 of the Crinoids obtained by the "Blake" expedition of 1877-78 he wrote 

 as follows : — " To this species (i.e., Antedon cubensis) I refer j^rovisionally two specimens 

 very much mutilated, having lost the cirrhi and the arms, differing somewhat from my 

 type specimen, but possibly the differences may be due to age." He then described an 

 individual dredged at Station 43 ("Blake") in 339 fathoms, to which I shall refer directly, 

 and added that a smaller and equally mutilated one had been previously dredged by 

 himself in 450 fathoms near Havana. 



These two specimens are quite different from the type of Antedon cubensis, and also, 

 though in a less degree, from one another. Not only are the first radials visible, and the 

 second but little shorter than broad, as was mentioned by Pourtales, but the first radials 

 are separated from the acorn-shaped centro-dorsal by a complete circlet of basals, and 

 there are no pinnules upon any of the first six arm-joints, which are the only ones 

 preserved. An equally mutdated specimen of Pourtales' second type was dredged by 

 the Challenger (1873) in 350 fathoms, off Barra Grande (PL VI. fig. 7); seven more 

 perfect ones, making nine in all, were obtained off Nevis, St. Lucia, and Granada, during 

 the cruise of the "Blake" in 1878-79, between 291 and 422 fathoms; while a single 

 example of a third species (PI. VI. fig. 5) was dredged by the Challenger in the 

 neighbourhood of Fiji, in the year 1874. 



These eleven individuals, representing three different species, are distinguished from 

 all other living Coniatulse by certain very definite morphological peculiarities, which 

 impart an interest to this type second only to that of the archaic Thaumatocrinus. Its 



1 Bidl. Mm. Comp. Zobl, 1869, vol. i. No. 11, p. 356. * Ibid., 1878, vol. v. No. 9, p. 214. 



