78 
very broad, except at the apex. The mouth organs in general 
are in near agreement with those which Bate has figured in 
the Challenger Macrura for P. canaliculatus, var. japonicus, 
and not essentially different from de Haan’s figures of these 
parts in P. semisulcatus, except that the endopod of the first 
maxillae is much more elongate than de Haan represents it. 
The biramous epipod is similar in structure on the second and 
third maxillipeds and the first three peraeopods. In all it is 
furnished with numerous sete of varying lengths, which have 
a formation worthy of notice. The distal part is biserrate, 
and just in front of the acute apex is thickened by a comb or 
brush of little close-set spinules on either side. Of the two 
widely divergent rami or processes one is much longer than 
the other. The basal joint to which the broad lamina is. 
attached is itself narrow and curved. The exopods of the 
second and third maxillipeds are long and many-jointed, 
fringed on either side with long plumose sete. Those on the 
first four peraeopods are small, narrow, unjointed, and carry 
a few sete similar to those on the epipods. On the fifth 
peraeopods, which have a pleuro-branchia, I have not found 
any exopod. These peraeopods are decidedly longer than the 
fourth pair, but both are much shorter than the third, in which 
as usual the wrist or fifth joint is conspicuous by its length. 
The first peraeopods are relatively stouter than the third, 
but much shorter; the second pair having an intermediate 
length. The finger in the third pair is shorter than the palm, 
sub-equal to it in the second, and longer than it in the first 
pair. In the first pair near the apex of the wrist on the lower 
side there is a small group of setules, while there is a group’ 
on the proximal end of the hand, suggesting a tentative effort 
at the quasi-prehensible arrangement more effectively carried 
out in the genus Sergestes. The second and third joints in 
the first peraeopods have each a sub-apical tooth. The second 
joint only in the second peraeopods is so armed. On the 
first pleopods of the male the petasma is small and not very 
complicated in structure, not differing very strikingly from 
the forms figured by Kishinouye for P. monodon and P. ashiaka. 
The thelycum between the fourth and fifth peraeopods of the 
female, in a specimen intermediate in size between the two 
males from which the other figures are drawn, shows two 
longitudinal plates pointing forwards to meet a transverse 
trilobed plate, with its middle lobe smaller and less advanced 
than the other two. In two other considerably larger female 
specimens in the collection the longitudinal plates are in close 
juxtaposition, concealing all but the middle lobe of the trans- 
verse plate. 
