Mr. W. N. Lockington on American Alphei. 469 
equal, compressed-oyate, spineless. Dac- 
tyli of posterior pairs spinulose........ B. equimanus! P. 
Front rounded; hands similar, fingers gaping 
pg Clb gee eae era Ah irre B. longidactylus! P. 
Alpheus clamator, Lockington. 
Alpheus clamator, Lockington, Proc. Cal. Acad. Sci. vii. 1876, p. 48. 
Alpheus transverso-dactylus, Kingsley, loc. cit. p. 197. 
Carapax smooth, body not greatly compressed. Front tri- 
spinose ; the rostrum longer and more slender than the ocular 
spines, which are separated from it by a deep sulcus, and 
widen out quickly into the eye-shield. 
Basal spine of antennule shorter than the first joint of the 
peduncle; outer branch of flagella stout, margined with sete, 
about equal in length to peduncle, inner branch about halt 
the length of the body. 
Antenne with a spine on basal joint. Antennal scale 
narrow ; its spine nearly, and its laminar portion quite, reaching 
the end of the antennary peduncle, which is slightly longer 
than that of antennule. Flagella more than three quarters 
the length of body. 
External maxillipeds extending slightly beyond peduncle 
of antenne. Meros of both hands of first pair smooth, com- 
pressed, with a slender spine at distal extremity above. Car- 
pus of smaller hand slightly longer than that of larger. 
Hands unequal, dissimilar. Fingers of smaller pair straight, 
parallel, slender, closely fitting, working vertically, about 
equal in length to palm; manus with a spine above articula- 
tion of dactylus, whole inner surface beset with long hairs. 
Larger hand smooth proximally, setose and complexly sul- 
cate distally. A large spine on the outer side continued 
backward as a carina, above the carina a deep sulcus ; a second 
spine at articulation of dactylus. A deep and wide sulcus 
commencing above the articulation of the dactylus, flanked 
internally by a sharp ridge, externally by a smooth, broad 
ridge separating it from the exterior sulcus. This superior 
sulcus is continued obliquely backwards along the upper 
surface of the hand; and from about the centre of its length 
a transverse constriction is continued down the inner side of 
the hand. Below the exterior spine a constriction divides the 
pollex from the palm. Dactylus short, curved so as to close 
horizontally, swollen at the extremity, extending beyond the 
ollex. Ischium and meros of second pair equal; carpus five- 
jointed, first four joints together equal to meros, third and 
fourth joints each half the length of the second, which is 
equal to the first ; fifth joint intermediate in length between 
