122 



STALK-EYED CRUSTACEA. 



i 

 ; 



Polycheles sculptus paciflcus Eax. 



Pkte a, Fig, 1, T, 



Bull. Mus. Comp. Zo5l., XXIV. 196, 1893. 



4 



This form differs from its Atlantic representative^ P. sculptus 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. 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 plcurce 

 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 pleura) is not so strongly produced for- 

 ward in the Pacific form as it is in the Atlantic. (Cf Figs. I'' 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. 



ii, 



a 



a 



a 



u 



a 



3392. 1270 



3393. 1020 



3394. 



3418. 

 3419. 

 3424. 



511 



G60 



772 

 676 



£i 



U 



u 



a 



cc 



a 



1 fern. 



3 males, 3 fem. 

 12 males, 20 fem 

 1 male, 1 fem. 

 1 fem. 

 1 fern. 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 : 



HV 



^ 



%\ 



Somites 



PleurobranchijB 



Artbrobranchiae 



Podobranchise 



Epipods 



i 



VIII 





 

 







IX 





 1 

 



X. 





 2 

 1 



r 



XI. 



1 



2 

 1 



r 



XII. 



1 

 2 

 1 



r 



xni. 

 1 

 2 

 1 



T 



XIV. 



1 ~- 





 

 



4 

 9 



4 



(5r) 



11+ (5 r) 



^ 



^ 



,^' 



■j?v 



-.i.1 



