THE SPIDER CRABS OF AMERICA 419 



MITHRAX (MITHRAX) SINENSIS Rathbun 



Plate 151, figs. 3 and 4; plate 260 



Mithrax sinensis Rathbun, Proc. U. S. Nat. Mus., vol. 15, 1892, p. 266, pi. 

 38, fig. 2 (type-locality, Gulf of California, 17 fathoms, Albatross station 

 3002; holotvpe, Cat. No. 16065, U.S. N. M.). 



Diagnosis. — Three spines on basal segment of antenna. Three 

 antero-lateral branchial prominences, subacute, scarcely spinous. 

 Three or four tubercles on anterior margin of arm. 



Description.— ^Csirsipace ovate, a little longer than broad, covered 

 with low tubercles some of which bear one or two granules ; cervical 

 and cardiac groove deep. Edge of marginal prominences granulate. 

 Rostral lobes short, broad, arcuate, separated by a narrow U-shaped 

 sinus. Besides the preorbital lobe, the orbit has 2 small teeth above, 

 a well-marked outer lobe and 2 strong teeth below, outside the 

 antenna. Antero-lateral protuberances behind the orbit 4, the last 

 one at the lateral angle, simple and acute, the others lobiform with 

 subacute tips, but subdivided into 2 or 3; the first or hepatic lobe is 

 the most prominent, the next lobe is the widest. A postlateral 

 tubercle is present. In a dorsal view, a row of subbranchial spines is 

 partially visible. 



Basal antennal joint tridentate, all the teeth visible from above, the 

 2 outer teeth subequal, the one at the outer angle well behind the 

 rostrum, the tooth at base of second joint small. Two subhepatic 

 granules. 



Chelipeds of adult male much longer and heavier than legs. Merus 

 tuberculous and spinous, 3 or 4 spines along the inner margin, 5 or 6 

 along the outer, 2 rows of spines or tubercles on upper surface, one 

 row on outer surface. Carpus granulate. Manus smooth, inflated. 

 Fingers short, stout, gape of male short, a small, acute tooth near 

 base of dactyl, both fingers crenulate, the propodal finger throughout, 

 the dactyl from tip to tooth. Legs furnished with fine, scattered 

 hairs and above, with spines. 



Color. — In alcohol reddish; hands of a deeper hue. 



Measurements. — Male (21951), length of carapace 13, width between 

 tips of lateral spines 12.4, width across subbranchial regions 12.9 mm. 



Range. — Gulf of California. Depth, 7 to 17 fathoms. 



Material examined. — See table, page 420. 



MITHRAX (MITHRAX) LAEVIMANUS Desbonne 



Plate 261 



Mithrax laevimanus Desbonne, in Desbonne and Schramm, Crust. Guade- 

 loupe, 1867, p. 7, pi. 1, figs. 1 and 2 (type-locality, Guadeloupe; cotype 

 in Paris Mus.). 



Mithrax laevimanus A. Milne Edwards, Crust. R^g. Mex., 1875, p. 94, pi. 

 21, figs. 2-2 b. 



