19g12,] R. B. SEyMOUR-SEWELL: Surface-Living Copepoda. 331 
terminates in a bifid rostrum, composed of two short, stout, 
blunt processes. 
The thorax presents only three free segments as, in addition 
to the 1st, the 4th and 5th segments are fused together. 
The abdomen consists of four segments of which the 2nd 
and 3rd are quite short, closely resembling those of P. crassirostris. 
The Ist segment is symmetrical and presents a well-marked genital 
swelling ventrally. The furcal rami are symmetrical, twice as 
long as broad, and terminate in four setae of nearly equal length. 
The proportions of the segments and furca are 15: 5: 5: 10: 8. 
The 1st antennae reach to the middle of the abdomen; they 
are composed of 24 free joints having the following relative 
proportions :— 
Segments— 
U2 3-14: 5-02 7..8._ 9. FO. 01, 12. 13 14.15. 10, 17. 18! 19. 20. 21. 22. 23, 24. 25. 
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There is a transverse row of minute spines present on the 
posterior aspect of segments 2 to g inclusive. 
The 2nd antennae and mouth parts are similar to those of 
other members oi the genus. 
The ist pair of legs. The 1st basal segment bears several 
scattered delicate spines on its anterior surface. The 2nd basal 
bears an internal marginal seta. The exopodite consists of three 
segments, of which the Ist bears a small spine distally on its 
external margin. ‘The 2nd is devoid of spines and the 3rd has the 
usual two marginal spines, and an end spine, which is extremely 
long and delicate and is equal in length to the whole exopodite. 
The endopodite consists of two segments, both devoid of spines. 
The 2nd pair of legs. The Ist basal carries an inner marginal 
seta and has delicate spines scattered over its anterior surface. 
The 2nd basal has no seta or spines. The Ist segment of the 
exopodite bears a corona of spines on its distal external border. 
The 2nd segment bears no spines in addition to the usual marginal 
one. The 3rd segment has a row of fine spinules, six to eight in 
number, on the proximal part of the margin and a corona of 
fine spines near the distal end; the terminal spine is nearly half as 
long again as the end segment. The endopodite is three-jointed 
and has a group of four long slender spines on the posterior aspect 
of the 2nd joint. 
The 37d and 4th pairs of legs. In both there is a row of 
spinules on the proximal part of the margin of exopod 3, anda 
few on exopod 2, and the 2nd joint of the endopodite has a group 
of four spines on its posterior surface. The 3rd leg differs from 
the 4th, however, in that the Ist basal bears a few scattered spines 
on its anterior surface which are absent on the 4th leg. 
The 5th pair of legs. ‘These are composed of two joints, the 
terminal joint bears two end spines, one long and the other quite 
short. The longer spine bears to the end joint the proportioaal 
lengths of 7 : 10, and the margin is serrated so that in reality it is 
