151 
thry between the IBr, and, distinguish it at once from any species 
of Comatula, and the absence of dorsal processes on the cirrus 
joints from the species of Comissia and Leptonemaster. The 
presence of all the pinnules prevents any chance of confusion with 
Comatilia. 
Family Zygometridæ. 
Genus Zygometra A. H. Clark. 
LZygometra 1907. A. H. Clark, Smiths. Misc. Coll. (Quart. Issue), Vol. 
Lygometra fluctuans (P. H. Carpenter). 
Antedon fluctuans 1884. P. H. Carpenter, Challenger” Reports, Vol. 
11, Zoology, p. 280; idem., Vol. 26, Zoology, p. 94, pl. VIN (1888). 
Zygometra elegans (part) 1907. A. H. Clark, Smiths. Misc. Coll. (Quart. 
Issue), Vol. 50, p. 348. 
Singapore. April 20, 1906. Two specimens; one has 
nineteen arms 70 mm. long; there are eight IIBr series, all 4 
(3 + 4), and a single IIIBr series, 2, developed internally; the 
cirri are XX, 25—28; the first joint is about twice as broad as 
long, the following gradually increasing in length to the fourth or 
fifth, which is squarish; the following three or four joints are 
similar, and the joints then gradually decrease in length, the 
terminal seven or eight being nearly twice as broad as long; the 
sixth and" following joints bear long sharp dorsal spines; the 
Opposing spine is long and slender, about as long as the diameter 
of the penultimate joint; the terminal claw is considerably longer 
than the penultimate joint, rather slender, and moderately curved. 
The cirri have the same strueture as those of the Thalass- 
ometrinæ; up to the distal half of the sixth joint they are dull 
and without dorsal spines, but beyond this point they have a 
highly polished surface, and bear long dorsal spines; the transition 
joint, however, does not decrease in diameter anteriorly as is usu- 
ally the case in the Thalassometrinæ, nor is it encircled by a 
dark band. 
