394 BULLETIN 129, UNITED STATES NATIONAL MUSEUM 



Color.— In alcohol, reddish brown; chelipeds lighter; fingers pinkish 

 red for their proximal half, tips white. 



Measurements. — Male, paratype, length of carapace to tips of horns 

 18.8, on median line 18, greatest width 16.5, width at base of lateral 

 spines 15.4, width at postocular teeth 11.2 mm. 



Material examined. — Andros Island, Bahamas; in sponges; 1888; 

 Frederick Stearns, collector; 5 males (1 is holotype), 1 young female 

 (42513). No other specimens are known. 



MITHRAX (MITHRAX) PILOSUS Rathbun 



Plate 138, fig. 3; plate 258 



Cancer aculeatus Herbst, Naturg. Krabben u. Krebse, vol. 1, 1790, p. 218, 

 pi. 18, fig. B, pi. 19, fig. 104 (type-locality, America; type in Berlin Mus.). 

 Not C. aculeatus O. Fabricius, 1780. 



Mithrax aculeatus Milne Edwards, Mag. ZooL, vol. 2, 1832, class 7, descrip- 

 tion. Not Rathbun, Proc. U. S. Nat. Mus., vol. 15, 1892, p. 264.— Gund- 

 LACH and ToRRALBAS, An. Acad. Habana, vol. 36, 1899 (1900), p. 328; 

 reprint, 1917, p. 16 (not Cangrejo Denton Parra, 1787, nor M. verrucosus 

 Milne Edwards, 1834). 



Mithrax pilosus Rathbun, Proc. U. S. Nat. Mus., vol. 15, 1892, p. 262, pi. 39 

 (type-locality, Abaco, Bahamas; male, holotype, Cat. No. 16299, U.S.N. M.). 



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

 four spines on propodites of ambulatory legs. Spines on proximal 

 half of upper surface of palm. 



Description. — Carapace ovate-orbicular; width without spines 

 greater than length in the old, less than length in the young. The 

 greatest width of the carapace is about midway of its length, measured 

 from rostral sinus. Surface covered with flattened tubercles which 

 are crowded together; from some of these which are larger arise 

 short spines or spiniform protuberances; the longest are 4 in a trans- 

 verse row on the gastric region and 6 or 8 on each branchial region. 

 Of the marginal spines there are 4 strong antero-lateral, each of 

 which has one or more secondary spines at base; 3 small postero- 

 lateral spines followed by tubercles at the posterior angle. Small 

 specimens have the dorsal surface of carapace, chelipeds and legs, 

 except the greater part of the chelae, covered with a dense tubular 

 pubescence; this disappears with age. Rostral horns small, outer 

 margins nearly parallel, tips hooked inward. Of about the same size 

 and shape are the antero-external spines of the basal antennal 

 segments which are uncommonly divergent. The segment is armed 

 with 2 other spines, smaller, straight, and acute, one on the orbital 

 margin, the other situated on a lower level at the base of the follow- 

 ing segment. The margin of the orbit bears 3 spines above, one 

 broad and hooked at outer angle and one below besides those belong- 

 ing to the antennal segment. 



