PART 5 A MONOGRAPH OF THE EXISTING CRINOIDS 505 



stalked crinoids of the .Sifeoya-Hxped., 1918, p. 233 (in key; range; references). — GiSLfiN, Ark. 

 Zool., vol. 19, No. 32, 1928, p. 10 (notes). 

 Adelometra angusiiradi'aln Gislen, Kiingl. Fj'siogr. Sallsk. Handl., new ser., vol. 45, No. 11, 1934, 

 pp. IS, 22. 



Description [iiiodifictl by A.M.C.]. — The centrodorsal is conical, 2.8 mm. in diam- 

 eter and 2.5 mm. in vertical height. The cirrus sockets are arranged in 10 regular 

 vertical columns with usually four to a column; the sockets of adjacent columns tend 

 to alternate in level. The interradial spaces between the columns arc wider than the 

 radial ones and are slightly hollowed. 



The cirri are XLII in number with up to 70 segments and may be 25 nun. in 

 length. They are almost straight for the first three-quarters of their length but are 

 lightly coiled towards the tip. The first three segments are short; the fourth to about 

 the fourteenth are longer than broad, but not more than a third again as long as broad; 

 the following segments become progressively shorter and each develops a forward pro- 

 jecting dorsal spine which becomes very prominent on the short terminal segments, 

 changing from a high crest, rounded in profile, to a more acute projection. The oppos- 

 ing spine is prominent and the terminal claw short and curved. 



The radials are short and are depressed at their lateral edges. The IBri are longer, 

 tapering distally and widely separated laterallj". The IBrj (a.xillaries) are pentagonal 

 with the proximal side only slightly convex. They are broader than long. 



The arms are 14 in number, about 45 mm. long. The IIBr series are 4 in three 

 cases and 2 in the other. [Note by A.M.C] Gislen (1928) writes that where there are 4 

 ossicles in the IIBr series the third and fourth are not united by syzygy. Carpenter 

 himself took these articulations for syzygies but commented that one of them at least 

 does not have the appearance of a syzygy. From an external examination I am inclined 

 to agree with Gislen ; certainly the joint is much more constricted than are the syzygies 

 in comparable positions in Oligophreate species. 



From the proximal edge of the IBrj to the second syzygy (where no IIBr series 

 intervenes) measures 8.5 mm. and the width at the first syzygy is 1.15 mm. 



The free undivided arms consist of about 100 brachials which are at first triangular, 

 then wedge-shaped, later becoming narrow and elongated. On brachials arising from 

 IIBr series the second sj'zygy appears to be delayed until the thirteenth and fourteenth 

 brachials, or even further distally. The distal intersyzygial interval varies between 

 two and seven (usually five or six) muscular articulations. 



One (almost?) complete Pd remains (1957); it is about 10 mm. long and has about 

 30 elongated segments, of which the basal are rather stout but those of the outer half 

 are very attenuate. Pi probably had about 20 segments measuring 8 mm.; all are 

 broken. P2 has 11 segments, 5 mm. long and P3 with 8 segments is 4 mm. long. All 

 these pinnules are similar in shape but are progressively shorter. The following ones 

 tend to increase in length and the distal pinnules are long and fihform with 16 to 18 

 segments measuring 8 to 9 mm. in length. They have no trace of spicules in the 

 ambulacra. 



The disk is naked and much incised, 9 mm. in diameter. The division series and the 

 lowest pinnules are somewhat webbed by perisome. 



Saccuh are abundant on the disk, arms and pinnules. 



Remarks. — This species presents a number of anomalies. The arms suggest that 

 it might possibly be the young of some species of IHmerometra or a related genus 

 but the arrangement of the cirrus sockets in definite columns, the large number of 



