80 University of California Publications in Zoology (Vou. 23 
Lockington 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 Lockington 
Plate 12, figure 2 
Betaeus longidactylus Lockington, Proce. Calif. Acad. Sci., 7, 35, 1877; 
Ann. Mag. Nat. Hist. (5), 1, 480, 1878. 
Alpheus longidactylus Holmes, Oceas. Papers Calif. Acad. Sci., 7, 190, 
1900. 
Betaeus longidactylus Rathbun, H. A. E., 10, 108, 1904; Baker, Rep. 
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 inuer 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 (Lockington). 
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. 
Remarks.— 
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 LysmMatTmpagz (PROCESSIDAE) 
Rostrum 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. 
