236 
interiorly and exteriorly, half again as broad as the median length ; the next two brachials are 
roughly oblong, the following becoming triangular, about as long as broad, and after the basal 
third of the arm wedge-shaped, and elongate distally. The distal edge of the brachials is 
rather prominent and finely spinous; their dorsal surface is longitudinally striate. 
Syzygies occur between the third and fourth brachials, again between the ninth and tenth 
and fourteenth and fifteenth, and distally at intervals of two oblique muscular articulations. 
The interradial portions of the perisome of the disk bear numerous calcareous concretions 
subequal in size w-hich, entirely and rather widely separated from each other, are elevated 
above the general surface in the shape of thick papillae. 
P, is relatively large and stout, and recalls P., in certain varieties of Oligonictra serri- 
pinna\ it is 6 mm. long, composed of 12 segments of which the first is about as long as 
broad, and the remainder about half again as long as broad ; the distal border on the outer 
side (away from the disk) is everted and finely spinous. 
P., is 3 mm. long with 10 segments; it resembles Pj but is proportionately smaller, and 
the outer segments have a greater development of spines. 
Pg is 3 mm. long with 10 segments, more slender than P,, the component segments 
more elongate with more everted and spinous distal ends. The following pinnules resemble Pg, 
but slowly increase in length. 
The distal pinnules are 7^mm. long, very slender, with 19 segments of which all but the 
first two are greatly elongated with swollen articulations and overlapping and spinous distal ends. 
P„ is absent from seven arms, and present on three. 
The colour in life is pale orange and yellow, according to a note b\- Mr F. ^l. Chamberlain. 
The specimen described in Cat. N" 36050 U. S. National Museum. 
2. Erythrovietra ncder (A. H. Clark). 
A. H. Cl.-\RK. Proc. U. S. National Museum, vol. 33, 1907, p. 146 [Antcdon ruber). 
Proc. U.S. National Museum, vol. 34, igoS, p. 316 [Erytlironietra ruber). 
Hypalometra A. H. Clark. 
The only species in the genus Hypalovictra is 
I. Hypaloiiict7'a defccta (P. H. Carpenter). 
P. H. Carpenter. "Challenger"' Reports. Comatulac, 1S88, pp. 54, 206, 207, 367, 368, 378 
{Antedon defecta). 
Hartlaub. Memoirs Mus. Comp. Zool., vol. 27, 19 12, N" 4, p. 38 1, pi. 6, tigs i — 4; pi. 14, 
fig. 1 1 {Antedon defecta). 
Nanometra A. H. Clark. 
Key to the Species of the (jenus Xanometra. 
a' Cirri LXX, 43 — 47, 25 mm. to 30 mm. long; distal borders of the radials and 
borders of the ossicles of the IBr series usually unmodified, rarely bearing tubercles; 
