256 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 21 



by comparison. Apparently northern specimens regularly attain a size 

 much greater than southern specimens, none of which are over 24 mm, 

 with an average size for adults of about 17 mm. 



The range of the species is extended southward from San Diego, 

 California, to San Carlos Point, Lower California, Mexico. 



Genus LOXORHYNCHUS Stimpson 



Loxorynchus Stimpson, 1857a, p. 84. 



Loxorhynchus, Stimpson, 1857b, p. 451 ; correction for Loxorynchus. 

 Rathbun, 1925, p. 198. 



Type: Loxorhynchus grandis Stimpson, by subsequent designation of 

 Miers (1879c, p. 652). 



Description: Carapace pyriform, more or less spinous and pubescent; 

 gastric region extensive, convex; hepatic region small, prominent, armed 

 with at least one stout spine. Rostrum bifid, more or less deflexed ; horns 

 divaricate. Orbits imperfect, interrupted above and below by a deep longi- 

 tudinal sinus, ocular cavity subtubular. Eyes rather short, retractile, 

 not hidden. Preorbital tooth strong ; postorbital spine acute, nearly longi- 

 tudinal, below it a small spine situated external to the basal article of the 

 antenna. Movable part of antenna scarcely concealed by rostrum, flagel- 

 lum long; immovable article broad, nearly quadrate, armed at external 

 apex with an acute, laterally extended spine. Epistome large, sub- 

 trapezoidal. External maxillipeds with inner angle of ischium strongly 

 produced and rounded. Legs subcylindrical, those of the second pair 

 [first walking legs] longer; dactyli short, nonspinulous. Digits of the 

 first pair [chelipeds] of male and female with denticulate margins. 



Abdomen 7-segmented [in both sexes]. (Stimpson, 1857b) 



Chelipeds of adult male much enlarged, fingers gaping, a large basal 

 tooth on the dactylus. Legs diminishing in length from first to fourth 

 pair. (Rathbun, 1925) 



Range: Pacific coast of North America from Point Reyes, California, 

 to Point San Bartolome, Lower California, Mexico. Shore to 110 

 fathoms. 



Contains two species of large size which occupy overlapping, although 

 not identical, ranges. 



Key to the Species of the Genus Loxorhynchus 



la. Carapace covered with many small spines ; two spines on hepatic 

 region. Front strongly deflexed. Cheliped of old male shorter 

 than first and second walking legs. Apex of male first pleopod 

 not flaring, tip bilobed . grandis 



