from 35 mm. to 90 mm. long 28 — 55 cirrus segments (from Madagas- 
car to the Kei Islands and southern Japan; 70 — 252 [? 273] 
Metres) Perometra 
b'- the ossicles of the IBr series and first two brachials may be just in 
contact laterally, but their sides are never sharijly flattened, and prominent 
synarthrial tubercles are never developed; their lateral borders always 
bear tubercles, one or many to each ossicle, and their distal and pro.ximal 
borders are usually prominently everted and tubercular 
c' interbrachial portions of the perisome naked-, P„ always present (Kei 
Islands and southern Japan; 204 — 344 Metres) .... Nanometra 
c- interbrachial portions of the perisome with numerous prominent rounded 
calcareous nodules which are not in lateral contact; P,; usually absent 
(Moluccas and southern Japan; 99 — 270 Metres). . . . Erythrometra 
Perometra A. H. Clark. 
Key to the Species of the Genus Perometra. 
a' Centrodorsal rounded conical ; cirri numerous, long and slender, XXX — XL, 
35 — 55i -5 "im- to 30 mm. long; arms 50 mm. long, or longer 
b^ II — 14 arms 50 mm. long; IIBr series 2; synarthrial tubercles greatly, but 
not extravagantly, developed; all of the earlier pinnules present (Providence 
Island, northeast of Madagascar; 225 Met res) afra 
b' 10 arms 70 mm. to 90 mm. long; synarthrial tubercles extravagantly developed; 
P,j usually absent (southern Japan, from the Korean Straits to 
Saga mi Bay; 70 — -250 [." 273] Metres) dioiiicdeac 
a" Centrodorsal low hemispherical; cirri XV, 28; 10 arms 35 mm. long; all the 
earlier pinnules present (K e i I si a n ds ; 252 Met res) . . pttsilla 
1. Perometra afra A. H. Clark. 
A. H. Clark. Proc U.S. National Museum, vol. 40, 191 1, p. 43 [Pcroiiittra afra). 
Smithsonian Miscellaneous Collections, vol. 61, 1913, X'^ 15, p. 57 (Perometra afra). 
2. Perometra diomedeae (A. H. Clark). 
A. H. Clark. Proc. U. S. National Museum, vol. 33, 1907, p. 146 [AiiteJon diomedeae)., 
— — Proc. U.S. National Museum, vol. 34, 1908, p. 316 [Perometra diomedeae). 
3. Perometra pttsijla (P. H. Carpenter). 
P. H. Carpenter. "Challenger" Reports. Comatulae, 1888, p. 131, pi. 23, fig. i [Antedon 
pusilla). 
A. H. Clark. Proc. U.S. National Museum, vol. 39, 191 1, p. 561 [Perometra pusilla). 
Smithsonian Miscellaneous Collections, vol. 61, 191 3, N" 15, p. 58 [Perometra fiisilla). 
