548 i'i,'ociJi:ni\(!s of rin: \.\tiox\l ursuiur. vol.:;,v 



Chelipeds short, stout; inner margin of arm laminate and spinous; 

 wrist spinulous; chelae flat;- tips of fingers narrow, slightly spoon- 

 shaped. Legs spinous and hairy; merus joints broad. Color dark, 

 purplish or brown, mottled with citrine on the carapace, yellowish 

 on the legs. 



Width 30 to 40 mm. 



Taken on the beach at Las Vacas, near (upon, January 23, 1908. "Chanduya," 

 common on muddy beaches; noted especially about the mangrove swamps. 



Not previously known from Pern. 



Distribution. — From Magdalena Bay, Lower California, to Peru. 



PACHYGRAPSUS TRANSVERSUS (Gibbes). 



Plate 4(i, rig. :'.. 



Grapsus I nmsversus Gibbes, Proc. Amer. Ass. Adv. Sri., vol. 3, 1850, p. 181. 

 Goniofjrapsus innotatus Dana, Crust. U. S. Expl. Exped., pt. 1, 1852, .p. 345; 

 atlas, 1855, pi. 21, fig. 9 a-c. 



A small species. Carapace trapezoidal, much broader than long 

 and much broader in front than behind; transversely and obliquely 

 striated; one tooth behind the outer tooth of the orbit. Front 

 inclined, more than half as wide as carapace, edge sinuous. Chelipeds 

 equal, stout, striated; inner lamina of arm distally laciniate; a. blunt 

 tooth on wrist; propodus with an obliquely longitudinal line near 

 lower edge; palm nearly smooth outside. Legs spinous at extremity 

 of upper and lower margins of merus; margins sparsely clothed with 

 long bristles; dactyli with long spines. 



Width 12 to 15 mm. 



on the beach at Laa Vacas, near Capon, January 23, 1908. 

 Oyster beds of Maiapalo, near Capon, January 23, 1908. 



Distribution. — From California to Peru; Galapagos Islands. Also 

 widely distributed in tropical Atlantic and Oriental Region. 



ARATUS PISONI (Milne Edwards). 



Plate 50, fig. I. 



Sesiirmn pisonii Mii.nk Edwards, Hist. Nat. Crust., vol. 2, L837, p. 7ii, pi. 19, 



fi<j:s. t and 5. 



Carapace trapezoidal, nearly as long as wide, very narrow behind; 

 regional furrows deep, sides striated. Front vertical, very wide, 

 showing lour lobes above and reaching nearly to the buccal cavity. 

 Chelipeds of moderate lengl h, stout in male; arm inwardly expanded : 

 outer surface of wrist obliquely elongate; claws t iiberciila.te, an oval 

 area on the outside is covered with long black bristles; lingers nar- 

 rowly gaping. Legs Hun. Hat, last two joints hairy on margins; two 

 spines at end of upper edge of merus joints; propodus very long; 

 dactyli very short . 



Width 20 to •_»."» nun. 



