122 STALK-EYED CRUSTACEA. 
Polycheles sculptus pacificus Fax. 
Plaie C.,Fig tof. 
Bull. Mus. Comp. Zodl., XXIV. 196, 1893. 
This form differs from its Atlantic representative, P. scudptus Smith 
(Pentacheles spinosus A. M. Edw.), as follows: the carapace is broader in pro- 
portion to the breadth of the abdomen, the lateral margins converging 
strongly at the posterior end, where, in P. scudptus, they continue nearly par- 
allel to one another ; there is a small spime on each branchial region inside 
of, and on a level with, the second spine of the submarginal carina, — this 
spine is entirely wanting in the type form from the Atlantic; the spine on 
the anterior border of the ophthalmic lobe is larger and blunter ; the pleurse 
of the second abdominal somite have a different shape, their anterior margins 
being in line with the anterior margin of the tergum, whereas in P. sculptus 
they form a strong obtuse angle with the anterior margin of the tergum. In 
other words the anterior part of these pleur is not so strongly produced for- 
ward in the Pacific form as it is in the Atlantic. (Cf. Figs. 1‘ and 2; Plate C.) 
These differences, though slight, are constant, and should be recognized in 
our nomenclature if any significance is attached to geographical variation. 
Station 3353. 695 fathoms. 1 male. 
eeaage, 120 a 1 fem. 
ss 3393:. 1020 <§< 3 males, 3 fem. 
ce 3004.) bit) < 12 males, 20 fem. 
Croton) VOO0i 5 ~ 5 1 male, 1 fem. 
CUO AN Ole mnigain <s 1 fem. 
Gc 3424. 676 S 1 fem. ovig. 
The last thoracic appendages are chelate in the adult female, while they 
are but imperfectly so in breeding males. That is, in the male the “ thumb” 
is very much shorter than the index. 
The arrangement of the gills is shown in the following table : — 
Somites VIII. 10. ke xy xm. NITIES LVis 
Pleurobranchiz 0 0 0 1 1 1 eae 
Arthrobranchie 0 1 2 2 2 2 Ose 
Podobranchiz 0 0 1 1 1 1 Ol ae 
Epipods 0 r iP r r r Oj (57) 
17+ (7r) 
