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University of California Publications in Zoology [Vol. 23 



face oblique, triangular, more or less swollen. Carapace and ambulatory legs 

 more or less hairy; dactyls quite short and stout, appearing shorter than propodi, 

 sensibly stouter than in P. hirsutiusculus. 



Dimensions. — Type: length 19.1 mm. See also Remarks below. 



Color. — Yellowish (Stimpson). The dactyls are of a bluish color with a longi- 

 tudinal reddish stripe on the sides; distal ends of the propodi bluish (Holmes). 

 In life antennae are reddish brown; upper surface of distal segment of peduncle 

 with a narrow golden stripe. Distal third of propodi of ambulatory legs blue or 

 white, suffused with blue proximally, the rest of joint marked with stripes of 

 bluish or greenish brown; dactyls blue, becoming white near tip, suffused with 

 pale reddish orange just before corneous claw, with three more or less distinct 

 bluish or greenish red-brown stripes. Large hand usually a dark bluish green, 

 fingers tipped with white, on small hand often edged with orange. 



Type Locality.- — Tomales Bay, California. 



a b 



Fig. 90. Pagurus samuelis; a, $, natural size; b, $, X 1% (U. S. N. M.). 



Distribution. — Humboldt County (Holmes) to San Diego, California (Rath- 

 bun). Japan (Stimpson, Ortmann, doubted by Holmes) (Balss). 



Remarks. — Figure a is that of a female true to type ; figure b, that of a young 

 male which still partially retains the beaded edge so characteristic of young males, 

 and young and adult females, the original description, and subsequent illustrations. 

 Examination of the extensive collection of this species in the IT. S. National 

 Museum showed that the large cheliped in the male becomes with age quite elongate 

 and smoothly granulate comparatively, the beaded outer edge of the hand dis- 

 appearing completely. The largest P. samuelis male I have seen was collected by 

 the Venice Marine Biological Station at the foot of the San Pedro Breakwater, 

 February 21, 1913, and measures 42 mm. from tip of rostrum to end of telson; 

 carapace is 18 mm. long, the anterior portion 7.5 mm., and length of the propodus, 

 carpus, and merus of the large cheliped, taken together, 28 mm. 



This is the first instance of sexual dimorphism in adult American hermit crabs 

 of which I am aware. The isolated adult male and female with respect to the 

 character of the large cheliped seem to be two very distinct species; in all other 

 characters, however, there is a close correspondence which precludes any separa- 

 tion. In a lot of over one hundred specimens from Pacific Grove both extremes 



