136 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



KEY TO THE SPECIES IN THE GENUS CYLLOMETRA 



o '. Over 40 cirrus segments; cirri with 41-46 segments, 20 mm. long; 11-16 arms about 70 mm. 



long (Mergui Archipelago; 119 meters) prashadi (p. 136) 



a ^ Not more than 35 (very seldom more than 30) cirrus segments. 



6 '. Cirri of moderate length or short, moderately stout, with the longest segments usually from 

 about as long as broad to half again as long as broad, and never more than twice as long 

 as broad (from southern Japan and the Bonin Islands to the Philippine, Kei, and Lesser 

 Sunda Islands, and westward to the Persian Gulf; 22 [?15]— 329 [?731] meters)_manca (p. 137) 

 b 2. Cirri long and slender, with the longest segments about twice as long as the proximal width 

 (Lesser Sunda Islands; 69 meters) gracilis (p. 169 



CYLLOMETRA PKASHADI A. H. Clark 



Plate 17, Figures 83-85 



CyUomelra prashadi A. H. Clark, Reo. Indian Mus., vol. 34, pt. 4, 1932, p. 551 (listed), p. 558 

 (Investigator station 535; description; comparisons), pi. 19, figs. 5-7. 



Diagnostic features. — The cirri have 41-46 segments and are 20 mm. long; the 

 11-16 arms are about 70 mm. long. 



Description. — The centrodorsal is broad, thin discoidal, with the dorsal pole 

 3.5 mm. in diameter, slightly raised in the center, depressed in the peripheral third, 

 and rising again at the bases of the cirri. The cirri are arranged in a single fairly 

 regular marginal row. 



The cirri are XV, 41-46 (usually nearer the latter), about 20 mm. long. The 

 first segment is about twice as broad as long or somewhat longer, and those following 

 gradually increase in length to about the eighth or tenth which, with those succeeding, 

 is from one-thu-d to one-half again as broad as long. The cirri taper slightly in the 

 distal third. On the third and following segments the dorsal surface rises consider- 

 ably from the proximal to the distal end, which is more or less raised in the middle 

 and is armed with fine spines. After the fifth or sixth the segments show dorsally 

 two terminally situated dorsal spines, one on either side. DistaUy these spines 

 gradually become more slender and longer, and slowly move proximally, on the fourth 

 segment before the penultimate coalescing into a transversely elongate tubercle 

 which on the antepenultimate becomes a simple median tubercle. The opposing 

 spine is low, median, with the apex transversely elongated, forming a short transverse 

 ridge with the crest strongly convex. The terminal claw is somewhat longer than 

 the penultimate segment, and is rather stout and rather strongly curved. 



The distal border of the radials is even with the rim of the centrodorsal in the 

 midradial line, but a considerable portion of the anterolateral part of the radials is 

 visible in the interradial angles. The anterolateral angles of adjacent radials are 

 separated by deep and rather broad notches. The IBri are very short and bandlike, 

 about eight times as broad as the median length, half again as long laterally as in 

 the median line. The lateral borders are rather strongly convergent, and they are 

 widely separated from their neighbors. A low and broadly rounded median elevation 

 occupies the middorsal line. The IBfj (axillaries) are very broadly pentagonal, 

 about twice as broad as long. Their lateral borders are about as long as those of the 

 IBri, with which they make an angle of about 120°. There is a prominent more or 

 less laterally compressed synarthrial tubercle on the articulation between the elements 

 of the IBr series. It is continued proximally into the middorsal elevation on the IBr, 

 and distally in the form of a similar elevation occupying the proximal half of the 



