1921] Schmitt: The Marine Decapod Crustacea of California 79 
Genus Betaeus Dana 
Hands inverted so that dactyls are on lower side. Rostrum wanting; front 
not spined, either emarginate between the eyes or evenly rounded. 
KEY TO THE CALIFORNIA SPECIES OF BETAEUS 
I. Front emarginate between the eyes. Hands subequal, oval; fingers with but 
slight gape. (From Point Arena to Laguna Beach.) 
harfordi, p. 79. 
II. Front rounded. Hands similar, long and narrow; fingers with a more or less 
wide gape. (Not known north of San Pedro.) 
longidactylus, p. 80. 
Betaeus harfordi (Kingsley) 
Alpheus harfordi Kingsley, Bull. U. S. Geol. Surv., 4, 198, 1878; Bull. 
Essex. Inst., 14, 124, pl. 2, fig. 4, 1883. 
Betaeus aequalis Lockington, Ann. Mag. Nat. Hist. (5), 1, 479, 1878. 
Alpheus aequalis Holmes, Occas. Papers Calif. Acad. Sci., 7, 189, pl. 3, 
fig. 47, 1900. 
Betaeus harfordi Rathbun, H. A. E., 10, 108, 1904; Hilton, Jour. Ent. 
Zool., Pomona Coll., 8, 67, 1916. 
a c 
Fig. 55. Betaeus harfordi; a, hand; b, dorsal view of anterior portion (after 
Kingsley); c, hand (after Holmes). 
Characters.—Front emarginate between the eyes. Hands oval, vertical, smooth, 
strongly compressed; dactyl slender, the inner margin straight or somewhat 
concave near the base; fixed finger much wider than the dactyl, the entire inner 
margin may be straight, or there may be a deep, rounded notch near the base; tips 
of the fingers curved and crossed when closed; inner margins pubescent, the rest 
of the hand naked. Basal spine of the antennules long and slender, reaching 
beyond middle of the second joint of peduncle, second joint about twice the length 
of the third. 
Dimensions.—Types: length 19 and 24 mm., length of carapace 6 and 8 mm., 
length of larger hand 6 and 8 mm., respectively. 
Color.—When fresh dark purple, in alcohol a light flesh tint (Lockington). 
Pale olive green, eggs translucent green (Hilton). 
Type Locality—Santa Cataiina Island, California. 
Distribution.—Point Arena to Laguna Beach, California. 
Remarks.—This species lives under the mantle of Haliotis rufescens Swains. 
(Lockington). ‘‘...but it is not confined to that habitat, for I found several 
specimens upon sea-urchins that were brought up from several feet of water at 
Catalina Island. Their color was a dark purple like the specimens described by 
