268 



centrodorsal is viewed dorsally. Their height is scarcelj more than sufficiënt to tnodify the 

 normally circular 1 itrodorsal to .1 pentagon, 



I li<- basals form a very narrow band of almost uniform height between the radials and 

 the centrodorsal, though they are slightly higher than elsewhere in tin- angles of the calyx 

 where their dorsal sur face is raised to form a proximal continuation ol the interradial ridges 

 on the centrodorsal. 



The radials are relatively long, distall y scarcely twice as broad as long in the median 

 line; in lateral view the protile of the dorsal surface is straight; the proximal edgé is somewhat 

 shorter than the distal. 



[Br, is regularly oblong, about one third again as broad as long, entirely free basally; 

 there is almost no incision of the proximal border; the (listal lateral angles are slightly out away. 



The axillaries are broadly pentagonal, slightly broader than long; their lateral edges 



slightly inward and downward so as to form, with the truncated anter-ior corners of the 



IBr . prominent water pores; similar pores occur between the first and second brachials, interiorly. 



The visceral mass is high and narrow, and the ambulacra reach the arms along- the 

 summits of mesentary-like perisomic bridges as in Gephyrocrinus and in Thalassocrinus. The 

 mouth is central. The disk is unplated. 



The arms resemble those of Atelecrinus wyvillii\ syzygies usually occur between 

 brachials 3 4"4i 6 -f 7 and io -|- 11, and distallv at intervals of three or four oblique 

 muscular articulations. 



The lowest pinnule (on two arms) is on the sixteenth brachial; the pinnules are small 

 and weak, long-jointed and strongly flattened. 



"Albatross" Stat. 5619. o°3S'oo"N., 127 14' 40" E., (Molucca Passage; Mareh Island bearing 

 S. 7 E., 7 miles distant); 435 fathoms (783 Metres); fine gray sand and mud. 



A specimen collected by the "Albatross" near the locality where the type was dredged 

 by the "Siboga" appears to belong to this species. The centrodorsal is somewhat more sharply 

 pointed. There are the same interradial furrows. The proximal interradial ridges, though 

 prominent, are more rounded. The basals are visible only in the interradial angles of the 

 calyx, in the form of low triangles with excessively produced lateral apices, which fail to meet 

 the similarly produced apices of those on either side. The radials are considerably shorter 

 than those ol the type. and when the specimen is viewed laterally their dorsal profiles make 

 considerably mor,- than in if les-, than, a right angle with each other. The ossicles of the 



IBr series are slightly shorter than those of the type, and the brachials also are proportionately 

 slightly shorter. This gives the animal a more robust and compact appearai 



Atelecrinus sulcatus differs from . /. wyvillii in having the centrodorsal, basals and 



ds all in intimate contact, there being no perisomic lacunae as in ./. voyvillii. The centro- 



al differs from that of ./. wyvilli in its more sharply conical form, its pentagonal base 



with interradial ridges proximally, passing int<> interradial furrows between the cirrus sockets, 



reater height of the lateral ridges bordering the cirrus sockets, and the absence of notches 



proximal border. 



