232 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL.21 



Atlantic analogue: None. A west coast of Lower California-Gulf of 

 California endemic species. 



Diagnosis: Rostrum thick, simple, broadly triangular above, spiniform 

 below. A small preorbital but no postorbital tooth. Branchial width 

 exceeding hepatic. Male manus with a laminiform crest. Ambulatory 

 legs slender, bare except for a setose projection at distal fourth of pro- 

 podus of first pair. Male first pleopod terminally truncate, tip coarse 

 and little projecting. 



Description: Carapace widest at the posterior of the two lateral 

 teeth, these teeth rather acute at their tips. Preorbital tooth small but 

 distinct and rather prominent. Rostrum in the outline of its upper side 

 oblong, in length about equaling the distance between the tips of the 

 preorbital teeth, with sides slightly converging to a place near the ex- 

 tremity, running abruptly to a triangular point. In its other characters, 

 the rostrum thick, with its upper and lower surfaces a little concave; 

 the lower surface triangular in shape, narrower than the upper, and 

 separated from it by a deep lateral groove. 



Body and ambulatory [legs] smooth and naked. Chelipeds pubescent; 

 carpus acutely carinated externally; hand broad, compressed, with the 

 upper margin acute or crested, crest laminiform, very prominent above 

 the insertion of the dactylus. Ambulatory [legs] slender, with no vestige 

 of a thumb-process on the penult segment, excepting in the first pair. 

 (Stimpson, modified) 



Material examined: Hancock expeditions and related material: 4 

 specimens from 3 stations. (See Table 45) Punta Palmilla, near San 

 Jose del Cabo, and Cabeza Ballena, Gulf of California, Mexico. 



California Academy of Sciences: San Marcos Island, Gulf of Cali- 

 fornia, Mexico, June, 1921, Johnson and Baker, collectors, one male 

 (of two males identified by M. J. Rathbun). 



Measurements: Male specimen: length 11.0 mm, branchial width 

 8.8 mm, hepatic width 7.55 mm, rostrum 1.9 mm, width 2.2 mm, 

 cheliped 10.5 mm, chela 4.6 mm, dactyl 2.3 mm, height of palm 2.3 

 mm, ambulatory legs ca. 12, 10, 9, and 7 mm, respectively (could not be 

 straightened completely for measurement). Female specimen: length 5.9 

 mm, branchial width 4.65 mm, hepatic width 4.1 mm. 

 Color in life: Uniform ochre. 



Habitat: On Sargassum liebmanni J. Agardh, as determined by Dr. 

 E. Yale Dawson. 

 Depth: Intertidal. 



