No. 10 garth: brachyuran fauna of the galapagos 387 



Diagnosis. — Male carapace anteriorly broad, posteriorly narrow; 

 female carapace broadened posteriorly as well. Front wide, rostral and 

 inner orbital teeth in the same transverse line. Five lateral teeth, excluding 

 outer orbital, the second and third fused at base, the fourth and fifth 

 reduced in the male, in the female the fifth only. 



Material examined. — None from the Galapagos Islands. The Han- 

 cock collections contain a considerable series of this species from Isabel 

 Island, Mexico, to Bahia Honda, Panama. 



Pitho sexdentata Bell 



Pitho sexdentata Bell, Proc. Zool. Soc. London, vol. 3, p. 172, 1835. 

 Rathbun,Bull. 129, U.S. Nat. Mus., p. 367, pi. 130, fig. 1 ; pi. 250, 

 figs. 5-9, and synonymy, 1925. Sivertsen, Med. fra det Zool. Mus. 

 Oslo, no. 38, p. 11, 1933. Crane, Zoologica, vol. 22, no. 3, p. 60, 

 1937. 



Type locality. — Galapagos Islands, sandy mud, 6 fms. 



Type. — Not extant. 



Range. — From Santa Inez Bank, Gulf of California (Crane), to 

 Galapagos Islands (Bell). 



Atlantic analogue. — P. mirabilis (Herbst). 



Diagnosis. — Carapace broadly rounded in both sexes, granulate and 

 hairy. Front narrow, rostral teeth acute. Six lateral marginal teeth, ex- 

 clusive of outer orbital, all acute, separated at their bases, the sixth 

 reduced in size and at a higher level. 



Material examined. — ^A cast from Galapagos Islands. The Hancock 

 collections contain specimens from Manta and Cape San Francisco, 

 Ecuador. 



Remarks. — ^A cast of P. sexdentata was picked up by a crew member 

 while beach combing. Since several days elapsed before it came to the 

 attention of the carcinologists, it was impossible to assign to it a more 

 exact locality than Galapagos. 



Genus MITHRAXLatreille, 1817 

 Key to the Galapagos Species of the Genus Mithrax 



A^ Carapace without oblique branchial furrows (Subgenus Mithrax) 

 B^ Rostral spines long, divergent; carapace longer than broad, 



spinulous M. (Mithrax) spinipes 



B^ Rostral horns short, tuberculate or subtruncate; carapace 



broader than long 



