32 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 24 



Range: Bahia de San Juanico and Bahia de la Magdalena, Baja 

 California; Gulf of California, from Punta Penasco south to Guay- 



mas. Shore to 25 fathoms. 



Petrolisthes agassizii Faxon 



Plate 20, fig. 4 



Petrolisthes agassizii Faxon, 1893, p. 174 (type locality, Panama 



[City?]) ; 1895, p. 69, pi. 15, figs. 1, la. 

 Petrolisthes edwardsii, Boone, 1931, p. 152, text-fig. 7. Not P. ed- 



wardsii (Saussure). 

 Petrolisthes agassizi, Haig, 1957b, p. 12. 



Previous records: 

 Panama. "Panama" [City?]: Albatross (Faxon). Isla Saboga, Islas de 



las Perlas: Mrs. S. D. Sturgis and W. G. Van Name (Boone) ; 



Askoy (Haig). 

 Colombia. Bahia Utria: Askoy (Haig). 



Diagnosis: Carapace with distinct, transverse, piliferous striations, 

 continuing across metabranchial regions; a single epibranchial spine; 

 front triangular; carpus three times as long as wide, anterior margin 

 with three low, wide-set, serrate-edged teeth, and surface with three 

 longitudinal rows of rugae; manus with small groups of flattened, 

 scalelike tubercles; merus of walking legs with a row of spines on an- 

 terior margin, that of legs 1 and 2 spined at posterodistal angle. 



Description: Carapace covered with distinct, transverse, piliferous 

 striations, scarcely interrupted at the grooves separating the various 

 regions, the latter well marked ; striations uninterrupted posterior to 

 cardiac region. Front triangular, with a deep median groove extend- 

 ing between protogastric lobes; a small supraocular spine, scarcely pro- 

 duced in larger specimens. Postorbital angle produced into a low dentic- 

 ulate tooth. A single epibranchial spine. 



First movable segment of antenna with a broad lamellar lobe, its 

 margin serrate; second granular; third nearly smooth; flagellum naked. 

 Outer maxillipeds rugose. 



Merus of chelipeds rugose, with a strong serrate lobe or tooth on 

 anterior margin. Carpus about three times as long as wide; armed on 

 anterior margin with three low, wide-set, spine-tipped teeth, denticulate 

 on margins; piliferous striations of dorsal surface broken up into three 

 longitudinal rows of rugae. Manus long and slender, covered with 

 small groups of flattened, scalelike tubercles scattered evenly over dor- 



