122 STALK-EYED CRUSTACEA. 



Polycheles sculptus pacificus Fax. 

 Plate C, Fig. 1, T. 



BuU. Mus. Comp, Zool.. XXIV. 196, 1893. 



This form differs from its Atlantic representative, P. sculptus Smith 

 {Pcntachcles spinosns 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. sculptus, they continue nearly par- 

 allel to one another ; there is a small spine 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 pleurae 

 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 pleurae 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. 



1 fern. 



3 males, 3 fem. 

 12 males, 20 fem. 

 1 male, 1 fem. 

 1 fem. 

 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 : — 



