530 BULLETIN 152, UNITED STATES NATIONAL MUSEUM 



frequently found under stones and dead corals. * * ♦ Common, 

 both on the reefs and rocky shores, at low tide." 



Measurements. — Male, forma typica (53742), entire length of cara- 

 pace 22.7, entire width of same 30.2, fronto-orbital width 19, width 

 of front 8.8 mm. Female, forma pulchella (48563), entire length of 

 carapace 18.5, entire width of same 25.3, fronto-orbital width 16, 

 width of front 7.4 mm. Male, forma hermudensis (42798), entire 

 length of carapace 24.6, entire width of same 33.2, fronto-orbital 

 width 21.9, width of front 10 mm. Female, forma trinidadensis 

 (56764), entire length of carapace 21.3, entire width 30.3, fronto- 

 orbital width 19.1, width of front 8.8 mm. 



Range. — Gulf of Mexico (west coast of Florida and Florida Keys), 

 Yucatan Channel, Cuba, Trinidad. 



Material examined. — See table, pages 528 and 529. 



Genus HETERACTAEA Lockington 



Heteradaea Lockington, Proc. California Acad. Sci., vol. 7, 1876 (1877), p. 07 

 [3]; type, H. pilosus Lockington=i7. lunata Milne Edwards and Lucas. 



Dorsal aspect hairy as in Pilumnus. Carapace approaching a typical 

 Xanthid form, little swollen. Fronto-orbital distance great, front 

 with a straight thick border. Orbital border thick, lobed below. 

 Antero-lateral border spinous. No palatal ridge. Carpus of am- 

 bulatory legs armed above with a raised crest in the shape of a horn. 

 Abdomen of male with third, fourth and fifth segments fused. 



Known only in tropical and subtropical waters of America. 



KEY TO THE SPECIES OF THE GENUS HETERACTAEA 



A^ Crest of carpus of ambulatory legs bearing only one horn. Orbit bilobed 

 below ceratopus, p. 530. 



A-. Crest of carpus of first three ambulatory legs bearing two horns. Orbit 

 trilobed below lunata, p. 532 . 



ANALOGOUS SPECIES ON OPPOSITE SIDES OF THE CONTINENT 



Atlantic Pacific 



ceratopus lunata 



HETERACTAEA CERATOPUS (Stimpson) 



Plate 212, Figures 5-8; Plate 213 



Pilumnus ceratopus Stimpson, Ann. Lye. Nat. Hist. New York, vol. 7, 1860, 

 p. 215 [87] (type-locality, Key Biscayne, Florida; type not extant). 



Pilumnus? Schramm, in Desbonne and Schramm, Crust. Guadeloupe, 1867, p. 33 , 

 pi. 3, figs. 9 and 10. 



Hcteractaea ceratopus A. Milne Edwards, Crust. Reg. Mex., 1880, p. 300, pi. 

 52, fig. 3-3d. 



Diagnosis. — Crest of carpus of all the ambulatory legs with a 

 single horn at distal end. Inferior orbital margin bilobed. 



Description. — Body clothed above with very short tufts of pubes- 

 cence somewhat irregularly arranged, leaving many open spaces; 



