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which are also further protected by a heavy ventral plating; the terminal seven .segments are 
verv small and delicate. P., is similar, 4.5 mm. long with 14 segments of with the .sixth-tenth 
are expanded to protect the gonads. Pj is 4 mm. long with 13 segments of which the fifth- 
ninth are expanded. P. is 3 mm. long with 10 segments, none of which are expanded; the 
pinnule is small and moderately stout. The following pinnules gradually increase in length, the 
distal pinnules being 5 mm. long with 11 or 12 segments. 
2^'^ Suborder MACROPHREATA. 
1. Family Antedonidae Norman (emended). 
Key to the Subfamilies of the F'amily Antedonidae. 
a^ Cirrus sockets arranged in definite columns on a conical or columnar, 
usually large, centrodorsal Z e n o m e t r i n a e 
a" Cirrus sockets arranged in transverse alternating rows, or irregularly, 
on a hemispherical to discoidal or conical centrodorsal 
b' the segments of the genital pinnules are much expanded, forming 
a roof over the gonads , . I s o m e t r i n a e 
b- the segments of the genital pinnules are not expanded 
c^ Pj is composed of numerous (usually more than 50 and never 
less than 30) short segments of which at least the first six 
or seven, and usually nearly all, are broader than long, and 
the distal are rarely more than twice as long as broad ; P, is ' 
about as long as, or longer than, P„ 
d^ one or more of the following pinnules resembles P^ . . H el i o m e t r i n ae 
d^ P„ and the following pinnules are composed of segments 
which, beyond the third or fourth, are much elongated. . T h y sa n o m e t r i nae 
c" Pj is composed for the most part of much elongated segments, 
though a few- of the basal segments may be short ; the distal 
segments are at least twice as long as broad 
d' the distal cirrus .segments are entirely without dorsal pro- 
cesses on their distal ends ; the cirri are usually (but not 
always) short, rarely with more than 20, never with more 
than 30, segments Antedoninae 
d- the di.stal cirrus segments always have the distal dorsal edge 
prominent, with the median portion more or less produced 
in the form of a dorsal spine, and the middorsal line more 
or less strongly carinate 
e^ P., resembles Pj, and always differs from the genital 
pinnules; P^ is freguently, and Pj occasionally, absent . Perometrinae 
