PART 1 GARTH : PACIFIC OXYRHYNCH A 163 



margins forming a scarcely arched line with the posterolateral margins. 

 External maxillipeds having their merus dilated on the outside and very 

 little notched on the inside for the insertion of the palpus. 



Chelipeds of the male terminating in fingers hollowed into a spoon 

 shape and touching only at their extremity. Hands more or less com- 

 pressed. Ambulatory legs robust and little elongate ; their dactyli pointed 

 and furnished below with some denticulations. 



Abdomen of the male narrow and composed of seven articles. (A. 

 Milne Edwards, modified) 



Range: West coast of North America from Scammon Lagoon, Lower 

 California, and Tepoca Bay, Gulf of California, Mexico, to Manta Bay, 

 Ecuador; Galapagos Islands; east coast of America from Beaufort, North 

 Carolina, to Cape St. Roque, Brazil. Shore to 45 fathoms ; exceptionally 

 (in the Atlantic) to 120 fathoms. 



Key to the Pacific American Species of Pitho 



la. Five lateral teeth, the second and third united at base, the 

 second and fifth reduced in size. Carapace sparsely and coarsely 

 granulate 



2a. Carapace rough and strongly tuberculate. Cheliped of adult 

 male scarcely longer than first walking leg. First free 

 antennal segment very broad. Male first pleopods distally 



lyre-shaped picteti 



2b. Carapace nearly smooth and but weakly tuberculate. Cheli- 

 ped of adult male greatly exceeding first walking leg. First 

 free antennal segment narrower than 2a. Male first pleopods 



nearly linear quinquedentata 



lb. Six lateral teeth, the second and third not united at base, all 

 teeth of uniform size except last ; last tooth smaller and situated 

 at a higher level. Carapace thickly and finely granulate and 

 hairy sexdentata 



Pitho sexdentata Bell 

 Plate J, Fig. 3 ; Plate 17, Fig. 2 



Pitho sexdentata Bell, 1835b, p. 172. Rathbun, 1910, p. 573; 1925, p. 



367, pi. 130, fig. 1 ; pi. 250, figs. 5-9. Boone, 1927, p. 152, fig. 47. 



Sivertsen, 1933, p. 11. Crane, 1937, p. 60; 1947, p. 72. Steinbeck 



and Ricketts, 1941, p. 466. Garth, 1946, p. 387. 

 Othonia sex-dentata, Bell, 1836, p. 56, pi. 12, figs. 1, la-d. Not White, 



1847, p. 9. 



