Kingsley.] 148 [March 5, 
externo-posterior portion of each branchial region, and a single one 
at the base of each horn of the rostrum. Rostrum short, bilobed; 
orbits with a single fissure above, below with a deep groove externally 
and a fissure further in. Antero-lateral margin with four teeth, be- 
sides the external orbital angle, the first rather obtuse, the rest acute, 
second the largest, the last the most acute and strongly hooked for-. 
ward ; behind this last is a small tooth on the postero-lateral margin ; 
a small tubercle on the subhepatic region a little in advance of the 
first antero-lateral tooth. The oblique ‘ridge running backward from 
the palatal region is tuberculate. Basal joint of antenna with a 
short obtuse tooth, the two last joints of the peduncle with a stiff 
bristle on the inner distal angle. Chelipeds moderate, meros with 
spiniform tubercles above, inner margin with two spines near the 
distal extremity; carpus and hand smooth, the latter compressed, the 
fingers not so long as the palm, not denticulate, and with no tooth on 
the dactylus at the base. Remaining feet stout; meral, carpal and 
propodal joints armed with spiniform tubercles, and together with the 
basal portion of the dactyli, covered with long, stout hairs; distal 
portion of dactyli naked, strongly curved. Two specimens were 
brought from Key West, Fla., by Dr. A. S. Packard, Jr. 
Length of carapax, 14 mm.; breadth, 17 mm.; ratio, 1: 1.21. 
It differs from M. nodosus, coronatus, areolatus, ruber and sculptus in 
having the antero-lateral margin four-toothed; from M. coronatus in its 
narrower carapax and rounder outline; from JV. cinetimanus in the 
broader carapax, the acute antero-lateral teeth and the absence of 
teeth on the fingers of the chelipeds; from MW. minutus and denticulatus 
in the same character of the fingers. 
Genus MrrHrax Leach, Stimpson. 
Mithrax trispinosus sp. n. 
Carapax depressed, pubescent, about as long as broad, surface 
granulate, with scattered tubercles. Of these there is one on each 
side of the median line near the base of the rostrum, three on each 
hepatic region, four on each branchial region near the base of the 
second tooth, and others posterior to these, a transverse row of four 
prominent ones, with smaller ones on each side, near the posterior 
margin. Rostrum short, depressed, bifid, each horn terminated by 
three spines. Orbits with two large fissures above, below with two 
broad, acute teeth. Antero-lateral margin with four sub-equal, 
slender, acute, curved teeth; a small one on the postero-lateral mar- 
