CRUSTACEA NORTH PACIFIC EXPLORING EXPEDITION 211 



331. CLIBANARIUS PACIFICUS Stimpson 



Clibanarius [^aciftcns Stimpson, Proc. Acad. Nat. Sci. Phila., x, p 247 

 [85], 1858. 



This species approaches so closely to C. aquabilis that a long ex- 

 amination was necessary before any specific difference was apparent. 

 The feet are. however, more hairy than in that species, the dactvli 

 of the ambulatory feet are somewhat longer, and the lower surfaces 

 of the hands generally smoother. When the hands differ in size, as 

 they sometimes do slightly, the right is generally the larger. Our 

 species is of a very dark bluish-olive color ; ambulatory feet bright 

 yellow ; fingers of the hand red. It is littoral, and thus dift"ers much 

 both in color and station from C. ccquabilis. Our largest specimen 

 is a male, one and a quarter inches in length. The length of the 

 carapax in the median line is 0.39; breadth of front, 0.16 inch. 



It differs from Pa gurus iucrqualis De Haan in its equal and more 

 spinous hands. 



Found among rocks in the lowest subregion of the littoral zone at 

 Tanega-sima and Ousima. 



Genus PAGURISTES Dana 



It is remarkable that a form so distinct as Paguristcs should 

 have been so long suffered to remain in the old genus Pa gurus, 

 while the peculiarities of its external generative apparatus, in both 

 male and female, were well known. We have here the only hermit 

 crab in which the first two pairs of abdominal members are devel- 

 oped into organs subservient to generation. In the male these are 

 adapted to the purposes of generation, as in the Brachyura. though 

 their form is more like those of Astacus, and they have a similar 

 position on the lower surface of the abdomen near its base. In the 

 female the anterior pair of appendages is small and situated at the 

 base of the abdomen, and there is a broad, oblique expansion or sac 

 on the left side of its soft body formed by a folding of the integu- 

 ment at the posterior margin of the fourth segment, enclosing a 

 pouch which serves to contain the eggs. 



The other essential characters of the genus may be stated as fol- 

 lows : Eyes long. Antennre short ; acicle robust. Chelipeds similar 

 in shape and generally subequal ; commissure of the hand vertical ; 

 fingers moving in a horizontal plane. Feet of the fourth pair not 

 subcheliform. 



It has a wide geographical distribution, species being found in all 



