770 BULLETIN 82, UNITED STATES NATIONAL MUSEUM VOLUME 1 



Diagnostic features. The extraordinary beadlike gonads, one sac to each segment 

 of the pinnules and the irregularly branched arms distinguish this species from the 

 rest of the genus. 



Characters. The type specimen consists of a single incomplete arm broken into 

 eight fragments, all but one of which evidently belong in a linear series. 



The total length of the specimen is 278 mm., and the basal portion is 4 mm. in 

 diameter. It is probable that at least 50 mm. of the basal part is missing, and 40 mm. 

 of the tip, so that the arm length of the living animal must have been nearly or quite 

 350 mm. This would give an expanse of 700 mm., and indicate a size approximately 

 the same as that of Heliometra glacialis var. maxima, the largest known comatulid 

 recent or fossil. 



In this specimen the gonads, instead of being ovoid or fusiform bodies as in all 

 other known comatulids, are broken up into a series of small beadlike sacs, approxi- 

 mately one to each of the greatly elongated pinnule segments, which are protected by 

 prominent calcareous plates. This may be due to sexual differentiation, but it seems 

 more probable that its significance is specific and, taken in connection with the very 

 large size, it certainly differentiates this species sharply from all the others in the 

 genus. 



This single arm is peculiar in being twice branched. The thirty-fourth brachial 

 from the proximal end as preserved is the hypozygal of a syzygial pair, the epizygal of 

 which has the distal face divided and bearing two brachials, each of which is but slightly 

 smaller than the more normal one would have been. On the left (as viewed dorsally) 

 the first brachial beyond this axillary is short and is united by syzygy to the brachial 

 succeeding. The first brachial on the right is twice as long, obliquely wedge-shaped, 

 with the longer side inward. These two brachials are interiorly united basally for about 

 four-fifths of the length of the left (smaller and shorter) brachial. The twenty-fifth 

 brachial further on bears a well-developed arm as large as the main trunk instead of the 

 usual pinnule; in this supernumerary arm the fourth and fifth brachials are united by 

 syzygy as in primary arms. 



When this specimen was placed side by side with the arms of T. rugosus from the 

 Hawaiian Islands, no essential differences were found beyond the proportionately 

 greater size and the somewhat different arrangement of the syzygies. 



Notes [BY A.M.C.]. In 1937 Mr. Clark described some fragments from John Mur- 

 ray station 158 off the Maldive Islands, which he declared are of the same species as 

 those taken by the Investigator. The longest piece, from the outer portion of an arm, 

 is 60 mm. long and 2 mm. broad. It consists of 34 brachials, of which there are 8 

 syzygial pairs, each separated from the next by 3 or 4 muscular articulations. The 

 brachials are about half again as long as broad with very oblique ends and are rather 

 strongly excavated on the shorter side. The pinnule is attached to the middle of the 

 longer side. Above the pinnule socket the brachial is excavated for the reception of 

 the pinnule when at rest. The pinnules bear along the ventral surface a linear series 

 of small eggs, one to each segment. 



Another fragment is 55 mm. long and 2.7 mm. wide at the base. On the eight- 

 eenth brachial from the base a short distal portion is regenerated, and on this is a 

 pentagonal axillary bearing two arms, one 12 mm. long with 8 brachials and the other 

 17 mm. long with 11 brachials. The two first brachials are united interiorly for over 

 half their lengths. Each bears a pinnule on the middle of the outer side. On one 



