I4S 
d' cirri with at most 27 (usually between 20 and 25) segments, short 
and stout; division series and arm bases well rounded dorsally, 
appearing narrow and only slightly flattened against their neigh- 
bours; 10 — 20 arms; division series 2 (Kei Islands to southern 
Japan and the Hawaiian Islands) Parametra 
d- cirri with more than 40 segments, long, slender or stout 
e' division series and arms very narrow, slender, strongly compres- 
sed laterally, sharply carinate throughout; cirri very long and 
very slender; 20 arms; division series 2 (Kei Islands to the 
Philippines, and northward to southern Japan) . Stenometra 
e- division series and arms usually stout, the latter well rounded 
/ dorsally. at least in the earlier portion ; the ossicles of the 
division series and the first two brachials are usually smooth 
dorsally, but may have a very slight median keel, which is not 
continued on to the arm bases 
f IIBr series 4(3+4); division series and arm bases very 
strongly rounded dorsally, the dorsal surface entirely free 
of spinules or carinate processes (Bay of Biscay to the 
Canaries and Ascension Island; southern and 
eastern Africa to the Moluccas and the Philip- 
pines) Crotalometra 
f- all division series 2 ; ossicles of the division series usually 
with a flattened dorsal surface, perfectly smooth, with swollen 
borders, or with a lateral, proximal and distal border of thickly 
set fine spinelets (Caribbean Sea; southwestern 
Indian Ocean to the Moluccas, the Philippines, 
the Hawaiian Islands and southern Japan). . Cosmiometra 
Crotalometra A. H. Clark. 
Key to the Species of the Genus Crotalometra. 
a^ Centrodorsal thick discoidal, with the large stout cirri arranged in an irregular 
partially double row about the periphery 
b^ about 30 cirrus segments of which the longest are about twice as long as 
broad; brachials from the first onward with the distal edges turned outward 
and produced, and the ossicles of the division series with the distal edges 
prominent, giving the animal a rugged appearance (Bay of Biscay to 
the Canary Islands; 882 — 1480 Metres) flava 
b- 40 — 50 cirrus segments, the longest only slightly longer than broad; division 
series and arm bases nearly or quite smooth (Bay of Biscay to As- 
cension Island; 755 — 1480 Metres) porrecta 
