638 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxsvt. 



addition have a low sharp ridge running along their exterior surface 

 at the base of the carinate processes; Po similar to P^ and of the same 

 length, but the low ridge just described may be traced to about the 

 twelfth joint; Pg 9 mm. long with nineteen joints, similar to the two 

 preceding j^innules, but slightly less stout; P^ small, 6 mm. long, 

 tapering rapidly in the proximal half and becoming very slender 

 distally, with sixteen joints, at first twice as broad as long, becoming- 

 squarish about the ninth, and longer than broad distally, the first six 

 joints carinate ' like those of the preceding pinnules; Pg similar, 

 5.5 mm. or 5 mm. long; P^ and the following pinnules G mm. long 

 with seventeen joints, at first twice as broad as long, becoming squar- 

 ish about the eighth and twice as long as broad terminally; the pin- 

 nules are about as stout basally as the two preceding, tapering rapidly 

 in the proximal half and becoming very slender distally; the carina- 

 tion of the proximal joints is slightly marked on the first four; this 

 carination later becomes restricted to the second and third joint only, 

 and disappears entirely in the outer half of the arm. 



7'ype-specimen. — Cat. No. 4 F.=^ V * i Indian Museum ; Pedro Shoal, 

 north of the Laccadive Islands. 



Cotype. — Cat. No. ^25480, U.S.N.M. ; from the same locality. 



HETEROMETRA SINGULARIS, new species. 



Centro-dorsal discoidal, the bare polar area flat, 1.5 mm. in diam- 

 eter; cirrus sockets arranged in a single crowded, more or less irreg- 

 lar marginal row. 



Cirri XVII, 21-25, 12 mm. long; first joint short, second about 

 twice as broad as long, third somewhat longer, fourth about as long 

 as broad, next two slightly longer than broad, the following grad- 

 ually decreasing in length, the terminal fifteen being one-third or 

 one-half again as broad as long; at the seventh subterminal dorsal 

 spines begin to develop which soon become long and prominent; 

 opi)osing spine large and long, much larger than the spines on the 

 preceding joints, triangular, the apex terminal, arising from the 

 whole surface of the penultimate joint and about equal to the diam- 

 eter of that joint in length; terminal claw nearly twice as long as 

 the penultimate joint, slender, abruptly curved proximally, becoming 

 nearly straight distally. 



Disk with a few calcareous granules in the anal area, especially on 

 the anal tube. 



Radials short, oblong, the dorsal surface with numerous prominent 

 rounded tubercles; IBr^ short, oblong, slightly over four times as 

 broad as long, in close lateral apposition; IBr, (axillary) broadly 

 pentagonal, almost triangular, twice as broad as long, the lateral 

 edges shorter than those of the IBrj ; IIBr 4(3-|-4) ; joints up to 

 and including the second brachial exteriorly and the fourth interiorly. 



