418 BULLETIN 129, UNITED STATES NATIONAL MUSEUM 



MITHRAX (MITHRAX) TUBERCULATUS Stimpson 



Plate 151, figs. 1 and 2 



Mithrax tuberculatus Stimpson, Ann. Lye. Nat. Hist. New York, vol. 7, 

 1860, p. 189 (type-localit}^. Cape St. Lucas, Lower California; cotypes, 

 Cat. No. 122S, M. C. Z., and Cat. No. 23178, U.S.N.M.). Probably not 

 M. tuherculalus Aurivillius, K. Svenska Vet.-Akad. Handl., Stockholm, 

 vol. 23, 1889, p. 57 (St. Barthelemy, 1 meter). 



Diagnosis. — Two rounded lobes and a spine on antero-lateral 

 margin. Carapace very granulate. Two or three tubercles on 

 anterior margin of arm. 



Description. — Carapace covered with granulate tubercles; inter- 

 spaces smooth (non-granulate), punctate; marginal projections gran- 

 ulate. Rostral horns short, broader than long, truncate, extremity 

 granulate, interspace nearly V-shaped. Preorbital lobe subrectangu- 

 lar, followed by two small, supra-orbital tubercles; outer orbital 

 tooth small, projecting outward, little advanced. Antero-lateral 

 margin furnished with two large lobes, the first hepatic, the second 

 branchial and more prominent, and a curved spine at the lateral angle; 

 a much smaller postero-lateral spine. Of the dorsal tubercles two 

 pairs are behind the rostral horns, followed by a transverse row of 5 ; 

 about 7 large tubercles on the branchial region, and 2 side by side on 

 the intestinal region. Small, low tubercles on the cardiac and meso- 

 gastric regions, and single granules on the posterior and postero- 

 lateral margins. 



Basal antennal article sub triangular, with a broad, curved, pointed, 

 apical tooth, less advanced than the rostrum, and a small tooth on 

 outer margin. Outside of this there is another suborbital tooth on 

 the carapace. Pterygostomian ridge tuberculate. 



Merus of cheliped tuberculate, 2 or 3 tubercles on inner edge, 5 on 

 outer edge. Carpus granulate. Hand smooth. Fingers little gaping, 

 feebly crenulate and denticulate within, but with a tooth on the 

 dactylus in old specimens. Legs thick, subcylindrical, nearly naked, 

 short-spinous or granulate above in double series, tomentose below. 



Color. — Dried specimens are cream-colored, mottled with carmine. 

 In old specimens the carmine predominates. (Stimpson.) 



Measurements. — Type male, length of carapace 34.8, greatest width 

 42.4 mm. (Stimpson.) Male (Panama), total length 13.3, total 

 width 15 mm. 



Range. — West coast of Mexico (from Cape St. Lucas) to Panama. 



Material examined.— 



Cape St. Lucas; John Xantus, collector; received from Mus. 

 Comp. Zool.; two males, one female, cotypes (23178), 13 males, 13 

 females (1 ovig.), cotypes (1228, M. C. Z."). 



Panama; Captain Field; 1 male (Phila. Acad.). 



