144 BULLETIN 97, UNITED STATES NATIONAL MUSEUM. 



length, third a little wider, its meriis over twice as wide as long; 

 fourth leg shortest, reaching end of carpus of third. 



Abdomen strongly narrowing distally for its first segment, then 

 moderately tapering to the penultimate segment, which is constricted 

 at middle; last segment rounded at tip. 



Description of female. — Much larger than male. Carapace and 

 abdomen soft and yielding; carapace more uneven, less deflexed pos- 

 teriorly and without an antero-lateral marginal line. Median groove 

 on gastric region very deep. 



Chelipeds smaller than in male; palm narrower, its sides nearly 

 parallel; fingers longer, less deflexed, not gaping, sharp-pointed, 

 tips crossing ; thumb without a terminal notch, but instead a shallow 

 lobe at middle of prehensile margin; edge of dactylus feebly sinuous. 



Legs more alike than in male; first leg reaching to middle of dac- 

 tylus of second ; fourth leg reaching beyond end of carpus of third ; 

 merus of third leg about twice as long as wide. 



VaHations. — In some males the antero-lateral angle is vertically 

 compressed and correspondingly thin, forming a laterally projecting 

 lobe. 



Color. — In life, grayish-white (Cooper). Specimens in formalin 

 from Doctor Fraser are as follows : General color of females orange- 

 rufous with patches of scarlet on the gastric regions. Eggs orange- 

 chrome. Male, orange-rufous, or dirty greenish-white with orange- 

 rufous spots on carapace and a few of the same on chelipeds and 

 legs. 1 female from Taylor Bay was entirely white in life. 



Bleasurements. — Male (17468), length of carapace 7.G, width of 

 same 13 mm. Female (17468), length of carapace 15.2, width of same 

 22.8 mm. 



Habitat. — Commensal in clams and according to Holmes, in the 

 cloaca of a large holothurian, Liosoma arenata [arenicolali Stimpson 

 (now Molpadia arenicola). I think that Holmes's specimen may be 

 P. harnharti. 



Range. — From Prince of Wales Island, Alaska, to Humboldt Bay, 

 California. San Pedro, California (Holmes). 



Material examined. — 



Cordova Bay, Prince of Wales Island, Alaska ; taken in pairs from 

 gill chambers of giant clams; June 16, 1897; steamer Albatross; 

 7 males, 5 females (4 ovig.) (21792). 



Beaver Harbor, British Columbia ; in shells of Schizothaerus nut- 

 taUii; July 12, 1888; steamer Albatross; 7 males, 9 females (7 ovig.) 

 (17468). ' 



Departure Bay, British Columbia; in Schizothaerus nuttallii; 

 1908; Geological Survey of Canada; 1 male, 1 female (40398). 



Denman Island, British Columbia; from clams; May 12. 1914; 

 steamer Albatross; 6 males, 8 females (6 ovig.) (48426). 



