I 12 
d- Pj similar to Pj, but shorter; first three or four pinnules exceedingly 
long, extremely slender, stift", composed of greatly elongated seg- 
ments; about 40 arms; 37 — 39 cirrus segments of which the 
eighth is a well marked transition segment ; the outer cirrus 
segments have a slightly produced distal edge and a median 
carination ; the opposing spine is double, forming two thick lobes, 
one on either side of the median line Kpimetra 
b" 10 arms 
c' the outer cirrus segments bear long and prominent dorsal spines, 
which may be single or paired, and are shorter than the proximal 
d^ more than 35 cirrus segments of which the outer are much shorter 
than the proximal, the latter being more or less elongated, and 
bearing paired dorsal spines ; pinnules long and very stiff, the 
component segments with very spinous distal ends; proximal pin- 
nules elongated, with greatly elongated segments; distal edges 
of the longer cirrus segments fringed with spines Colobometra 
d'- less than 35 cirrus segments of which the outer are but slightly 
shorter than the proximal and bear single median dorsal spines ; 
pinnules short and somewhat stiffened, the component segments 
with spinous distal ends; proximal pinnules short, with short 
segments; distal edges of the cirrus segments smooth .... Cotylometra 
c- the outer cirrus segments bear a serrate transverse ridge dorsally, 
and are as long as, or slighdy longer than, the proximal 
d' Pj resembling P.,, and of about the same length - 
e^ 25 or more cirrus segments, all of which are broader than 
long; the segments of the long and stiff Pj and Pj have 
smooth distal edges Petasometra 
e- 23 or fewer cirrus segments, the third-sixth and following 
about as long as broad; the segments of the long stiff lower 
pinnules have very spinous distal ends Prometra 
d'- P, shorter, more slender, and weaker than P., 
most, or all, of the cirrus segments broader than long; P, 
(and P3 if enlarged) distally usually more or less flagellate; 
no lateral processes and few or no spines on the edges of 
the segments of the lower pinnules Decametra 
all but the basal cirrus segments about as lonsf as broad; 
enlarged proximal pinnules commonly spine-like, without a 
flagellate tip, the distal edges of the segments bearing lateral 
processes or long spines 
f enlarged lower pinnules with elongated segments which 
have very spinous distal ends Prometra 
»i 
