72 
III. Family Himerometridae A. H. Clark. 
Key to the Genera of the Family Himerometridae. 
a^ Pd longer and stouter than Pj, which in turn is longer and stouter than 
P„; division series narrow, strongly rounded dorsally, widely separated; 
IIIBr series on the outer side of each IIBr series 4 (3 + 4)1 on the inner 
side usually 2 ; large and robust species with from 20 to 65 (rarely less 
than 30) arms which are usually between 100 mm. and 150 mm. long 
(Persian Gulf to the Kei Islands, the x-\dmiralty Islands, 
St. Mathias Island, the Philippines and Cochin China) . . . 
a- Pd shorter and more slender than P^, which in turn is shorter and more 
slender than P, (in ten armed types Pj is shorter and more slender than 
P„, and the latter is shorter and more slender than Pg) 
b^ more than 10 arms 
c^ cirri very slightly curved (nearly straight), gradually tapering to 
a sharp point distally, the distal segments proportionately as 
long as, or longer than, the proximal, twice as long as broad 
or even longer, and entirely without dorsal processes; no opposing 
spine; terminal claw long and nearly straight 
d^ cirri very long and stout, the proximal portion light in 
colour, each segment with a ventral purple saddle, the 
distal portion dark brown, composed of 42 — 46 segments; 
division series usually broad, well rounded dorsally, not in 
lateral contact; large and robust species with from 20 to 
36 arms usually between 100 mm. and 130 mm. in length 
(Burma to Hong Kong, and southward to the 
Andaman Islands and Sydney, New South Wales) 
d- cirri small, very slender, entirely white in colour, composed 
of 25 — 30 segments; 10 or 1 1 arms from 70 mm. to 90 mm. 
in length (A rafu ra Sea; M oluccas) 
c" cirri not especially long and not noticeably stout; the distal 
portion is more or less strongly recurved; the distal cirrus segments 
are always much shorter than the proximal and usually bear 
more or less prominent dorsal spines, more rarely being simply 
carinate dorsally; the opposing spine is always well developed 
and prominent; the terminal claw is of moderate length or short, 
strongly curved (east Africa from Madagascar and 
Bagamoyo to Suez, eastward to the Moluccas and 
northern Australia, and northward to southern Japan) 
b" 10 arms only 
Himerometra 
Craspedometra 
Homalometra 
Heterometra 
