80 University of California Publications in Zoology [Vol. 23 



Loekington and resembled the color of the sea-urchins in whose spines they were 

 entangled when captured. At Point Arena I captured from under a rock at low 

 tide a single specimen which was nearly white." (Holmes.) Found in kelp hold- 

 fasts (Hilton). 



Betaeus longidactylus Loekington 



Plate 12, figure 2 



Betaeus longidactylus Loekington, Proc. Calif. Acad. Sci., 7, 35, 1877 ; 



Ann. Mag. Nat. Hist. (5), 1, 480, 1878. 

 Alpheus longidactylus Holmes, Occas. Papers Calif. Acad. Sci., 7, 190, 



1900. 

 Betaeus longidactylus Eathbun, H. A. E., 10, 108, 1904; Baker, Eep. 



Laguna Mar. Lab., 1, 106, 1912. 



Characters. — Front rounded, scarcely notched at the center even rarely. Hands 

 large, oblong, compressed, scabrous, the margins rounded, their length much 

 exceeding that of all the preceding joints combined; fingers slender, widely gaping, 

 longer than the palm, the tips furnished with small, curved, corneous claws, which 

 are crossed when the fingers are closed; fixed finger with a large tooth a little 

 behind the middle of the inner margin and a small, round tooth at the base. Basal 

 spine of the antennules long and slender, about reaching the tip of the second 

 joint of peduncle, second and third joints subequal. 



Dimensions. — Type: length 38.4 mm., length of larger hand 14.2 mm., of 

 smaller hand 9.1 mm. 



Color. — Color of carapace of dried (type) specimen green, with nuances of 

 russet and olive; fingers of larger hand light red, the tips green (Loekington). 

 The color varies in living specimens from olive green to olive brown ; the legs are 

 reddish, and in many specimens there is a light colored dorsal stripe along the 

 middle of the body (Holmes). Blackish, bluish green in life, with whitish stripe 

 on median dorsal line of abdomen, and a white fleck above each of the points of 

 articulation of the epimera ; tail-fan of darker color, almost black-green ; anten- 

 nules and antennae brownish green, antennal scale blue with white markings ; legs 

 purplish brown with extreme distal portions of propodus and dactylus clear white. 



Type Locality. — San Diego, California, on a sandy mud flat, between tides. 



Distribution. — San Pedro to San Diego, California. 



Bernards. — 



The unequal size of the chelipeds (of the type) is exceptional. I have col- 

 lected numerous specimens of this species at San Pedro, California, where it is 

 found in abundance in tide pools on a rocky ledge near the entrance to the harbor. 

 The hands are similar, generally equal, and very much larger in adult males 

 than in young males and females. The anterior margin of the carapace in some 

 specimens is slightly convex, in others straight, while in a few it is slightly 

 concave. In many adult females, and to a less extent in adult males also, the 

 dorsal surface of the carapace is bulged upward, owing, doubtless, to the enlarge- 

 ment of the ovaries or testes. Many of the specimens were infested with a 

 parasitic isopod attached to the under side of the abdomen (Holmes). 



Family Lysmatidae (Processidae) 



Bostrum horizontal with dorsal surface of carapace. Mandibles without incisor 

 process and without palp. First pair of legs more or less chelate. Second pair, 

 minutely chelate, slender, with segmented carpus. 



