260 CRABS OF THE FAMILY PERICERIDA—RATHBUN. 
and differs in some respects. The original description says that there 
are seven or eight lateral spines (A. Milne Edwards says six or seven), 
and in the figure there are six besides the postorbital. In our speci- 
men there are five besides the postorbital, the fourth being the longest 
and defining the lateral angle of the carapace, the fifth shorter than 
the others and elevated a little on the branchial region. 
The granules of the anterior two-thirds of the carapace are very 
inconspicuous. There are two large granules on the median line of the 
cardiac region, five or six granules on the posterior half of the branch- 
ial region, and a conspicuous row of four spiny granules on the intestinal 
region, making a curve concave to the posterior margin. The two teeth 
on the upper margin of the orbit are minutely serrate. The orbital 
sinuses are deeper than in other species of Mithrax. 
Spine at antero-external angle of basal antennal joint about half as 
long as the rostrum; remaining tooth spiniform. 
Chelipeds in our specimens shorter than the first pair of ambulatory 
legs. Merus spiny, bearing on the anterior part of its upper margin 
one or two spineslongerand more slender than therest. Carpus tubercu- 
lous, some of the tubercles spiny. Hands slender, smooth. Fingers 
spoon-shaped, finely dentate, when closed showing but a faint hiatus. 
Ambulatory legs pubescent, third and fourth joints with long spines 
above, third joint with small spines below. 
Length from base of rostral horns, 11 millimeters; width, without 
spines, 8.2 millimeters. 
Lat. 24° 55/15” N., long. 110° 39’ W., 33 fathoms, fine gray sand, 
broken shells, temperature 64.59, station 3001, U. S. Fish Commission, 
1889 (16064). 
Bell records this species from the Galapagos Islands, 16 fathoms, and 
St. Elena, 6 fathoms. 
Mithrax (Nemausa) acuticornis (Stimpson). 
Plate XxxvUJ, fig. 1. 
Mithrax acuticornis Stimpson, Bull. Mus. Comp. Zo6l., u, p. 116, 1870. A. Milne Ed- 
wards, Miss. Sci. au Mexique, pt. 5, 1, p. 98, 1875. Miers, Challenger Rept., Zo61., 
XVU, pp, 86, 88, 1886. 
Mithrax (?) sp., Kendall, Bull. U. 8. Fish Commission, 1x, p. 303, 1889 (1891). 
Stimpson says, ‘*The margin of the orbit is armed with six spiniform 
teeth, not including those of the antennal joint.” In some of the spec- 
imens examined the tooth on the inferior margin of the orbit next to 
the basal antennal joint is obliterated, leaving only five orbital teeth; 
three on the superior margin, one at the external angle, and one on the 
inferior margin. 
The following are the dimensions of three specimens, the length 
measured from the base of the rostrum, and the width, not including 
thespines. No.1. Length 15; width 10 millimeters; ratio 1:.77. No.2. 
