182 CALIFORNIA ACADEMY OF SCIENCES. 



Anterior chelipeds stout, often very unequal. Second pair filiform, carpus 

 cylindrical, annulated, hands small. 



Type. — A. rapax Fabr. 



Key to the Species of Alpheus. 



Front with a rostrum. 



A spine on the infero-distal angle of the merus of the - ^e^Ttt io<»s 



ambulatory legs A. clamator. 



No meral spine. 



No spine on the second basal antennal joint A. barbara. 



A spine on the basal antennal joint. 

 Front trispinose. 



Fingers of larger hand longitudinal; dactyl 



working nearly vertically A. equidactylus. ' 



Fingers of large hand not longitudinal; dactyl 



short, curved, working horizontally. . .A. belUmanus.^ 



Front with but one spine A. calif orniensis. '" 



Front devoid of a rostrum; dactyl joined to the lower side of 



the hand (Genus Betceus Dana). r V\o^r^\<ir<^\ 



Front emarginate in the center; hands oval A. cequalis. 



Front not emarginate in the center; hands long and 



narrow A. longidactylus. 



Alpheus clamator Lock. 



LINGT0N,Tr( 



Alpheus clamator LocKiNGTON,T*roc. Cal. Acad. Sci., Vol. VII, 1877, p. 43; 



Ann. Nat. Hist. (5), Vol. I, 1878, p. 469. Kingsley, Bull. Essex Inst., 



Vol. X, 1878, p. 58; Ibid., Vol. XIV, 1883, p. 117. 

 Alpheus transverso-dactylus Kingsley, Bull. U.S. Geol. Sur., Vol. IV. No. 



1, 1878, p. 196; Bull. Essex Inst., Vol. X, 1878, p. 58. 

 Alpheus candei Kingsley (not Guerin), Bull. Essex Inst., Vol. XIV, 1883, 



p. 124. 



Front trispinose, the median spine short and separated by a deep sulcus 

 from the small, acute, lateral spines which project nearly as far forward. 

 Antero-lateral angle of the carapace devoid of a spine. Basal spine of the 

 antennules broad, scarcely reaching the extremity of the first joint; second 

 joint about twice as long as the third; outer branch of the flagellum much 

 shorter than the inner one, the slender terminal portion shorter than the 

 basal part; inner flagellum longer than the carapace. Second joint of the 

 antenna with a spine below the articulation of the acicle; acicle narrow, 

 nearly as long as the peduncle, with the outer side concave and ending in 

 a strong spine which is separated by a deep, narrow cleft from the mem- 

 branous inner portion; flagellum longer or shorter than the body, Max- 

 illipeds about equaling the antennal peduncle. Chelipeds very unequal; 



