269 



2. Atelecrinus anomalus A. H. Clark. 



A. H. Clark. Notes frofn the Leyden Museum, vol. 34, 191 2, p. 153. 

 Stat. 177. 2°24'.5S., I29°38'.5E. Ceram Sea. 1633 Metres. 1 Ex. 



Centrodorsal very long, about 1.8 mm. braad at the base and 3 mm. long radially, 

 cylindrical in the proximal third, from that point onward (beginning rather abruptly) conical ; 

 the apex is rounded. The cirrus sockets are moderate in size, and are arranged in ten evenly 

 spaced columns, three (rarely two or four) to a column. Each column is separated from its 

 neighbors in the same column by about the distance 

 that the columns are apart. The surface of the centro- 

 dorsal is smooth and undifferentiated ; the cirrus sockets 

 are simple excavations, without the raised borders 

 usually found in the species of this genus; in each 

 cirrus socket just above the midclle a half conical 

 ridse makes in from either side; these ridges are 

 triangular in outline, the apex of the triangle abutting 

 on the central canal. The ligament areas above 

 (proximal to) these ridges are rounded proximally, 

 the sides converging in a sharp angle at the central 

 canal ; their area is approximately equal to that of 

 the ridges ; the ligament areas below (distal to) these 

 ridges are shallower, occupying about half the area 

 of the cirrus socket or rather more. The interradial 

 portions of the centrodorsal just below the basals are 

 slightly raised above the general surface, so that a 

 section of the centrodorsal through the base is rouncled- 

 pentagonal. The cirrus sockets occur almost exclusively 

 on the conical outer two thirds of the centrodorsal. 



The cirri are XXX, 19 — 20, about 13 mm. 

 long ; the first two segments are about twice as broad as long, the third is slightly broader 

 than long, or about as long as broad, the fourth is twice as long as the diameter of its ends, 

 the fifth is nearly or quite three times as long as the diameter of its ends, and the sixth is 

 slightly shorter; the following decrease gradually in length, so that the fourteenth and following 

 are only slightly longer than broad; the fourth-seventh are moderately constricted centrally, 

 but this central constriction disappears in the next two or three following, when the cirri 

 become strongly compressed laterally. The opposing spine is terminal, small and blunt. The 

 terminal claw is slightly longer than the penultimate segment, rather stout, evenly tapering, 

 and rather strongly curved. 



The short cirri of the species, which have short segments distally ancl a stout strongly 

 curved terminal claw, are very different from the very long and slender type heretofore 

 supposed to be characteristic of the species of Atelecrinus. It seems that in Atelecrinus we 



iig. 17. 



I.ateral view of a specimen of Atelecrinus anomalus 

 from Stat. 177. X 6 - (Courtesy of the L'. S. National 

 Museum). 



