THE SPIDER CRABS OF AMERICA 327 



LIBINIA SETOSA Lockington 



Plate 243 



Libinia canaliculata? Lockixgtox, Proc. California Acad. Sci., vol. 7, 1876 

 (1877), p. 67 [5]. 



Libinia affinisf Lockingto.v, Proc. California Acad. Sci., vol. 7, 1876 (1877), 

 p. 67 [5]. 



Libinia setosa Lockington, Proc. California Acad. Sci.. vol. 7, 1876 (1877), 

 p. 68 [6] (type-locality, San Bartolom6 Bay, Lower California; type not 

 extant).— Rathbun, Proc. U. S. Nat. Mus", vol. 15, 1892, p. 238, pi. 28; 

 vol. 21, 1898, p. 574. 



Libinia semizonale Streets, Bull. U. S. Nat. Mus., No. 7, 1877, p. 103 (type- 

 locality. Lower California; holotype. Cat. No. 2300, U.S.N. M.). 



Diagnosis. — Rostrum ascending, channeled below. Median spines 

 of carapace 8; 2 superhepatic spines; a rhomb of 4 on branchial region. 



Description. — Carapace broadly pyriform, its width less than the 

 postfrontal length. Rostrum ascending, not widened at the extrem- 

 ity, emarginate, forming two shallow teeth which are shorter in old 

 than in young; rostrum arched from side to side, bordered with a 

 fringe of hair, and forming with the rather rigid antennae which are 

 similarly fringed, an expiratory channel. 



Median spines 8. of which 4 are gastric, 1 genital, 2 cardiac and 1 

 intestinal; a single spine on each side of the anterior gastric spine; 

 2 marginal spines, 1 branchial, the other subhepatic ; 4 dorsal branchial 

 spines, of which 2 form a slightly curved line with the marginal spine 

 and the posterior cardiac spine, and the other 2 are in line with the 

 genital spine. A prominent preocular spine. Two hepatic spines, 

 one above the other; a subbranchial spine, below the epimeral suture. 

 A small spine or two on either side above the postlateral margin. Two 

 stout pterygostomian spines, the posterior one very blunt; a spine at 

 antero-external angle of basal antennal segment; a spine just behind 

 the outer margin of that segment. 



Chelipeds of old male much longer than ambulatory legs, stout, 

 finely granulate; palm not widening much toward fingers; dactylus 

 % as long as upper margin of palm; fingers gaping in basal half. 

 Legs stout and rather short. 



Variations. — In the old the spines are small, or reduced to sharp 

 tubercles or, as in the case of the postlateral tubercles, obsolete. In 

 the young, 18 mm. or less in length, 1 1 spines are very long and the rest 

 small; the long spines are 3 median (penultimate gastric, anterior 

 cardiac and intestinal), and 4 branchial (paired) forming 2 transverse 

 lines on the carapace; posterior gastric spine wanting. 



Measurements. — Largest male (19523), total length of carapace 95 

 mm., total width 75.6 mm. 



Range. — Lower California, Mexico, where so far as known it has 

 been taken onlv on the west coast. 



