CORYSTOIDEA. 299 



of the middle of the carapax, and the antero-lateral regions constitute 

 about three-fourths of the whole surface. In other species, however, 

 as of Corystes and Dicera, the antero-lateral margin appears to be very 

 short, although as to the regions of the surface nearly as above de- 

 scribed ; but this point requires fuller investigation. 



FAMILY I. TRICHOCERID^. 



GENUS TRICHOCERA, De Haan. 



TRICHOCEEA OREGOJSTENSIS. 



Carapax transvcrsus, canvexus, gibbosus, granulosus, anticd lateraliterque 

 bene arcuatus, angulo laterali vix instructm, margine laterali (postero- 

 laterali incluso) dentato, 13 dentibus, regularibus, brevibus ; margine 

 postero-laterall recto; f route inter-antennali brevi, recto, medium non 

 emarginato. Pedes antici crassi, manu perbrevi, altd, superne minute~ 

 tuberculatd, extits Icevi et obsolete 5-costatd. Pedes 8 postici pubes- 

 centes. 



Carapax transverse, convex, gibbous, granulous anteriorly, either 

 side arcuate, and hardly having an angle on the lateral margin, 

 this whole margin (including the postero-lateral) , dentate with 

 thirteen short, regular teeth, postero-lateral margin straight ; inter- 

 antennary front short, straight, not emarginate at middle. Anterior 

 feet stout, hand very short, high, minutely tuberculate above, outer 

 surface smooth, and having five exceedingly slender costae. Eight 

 posterior feet pubescent. 



Plate 18, fig. 5 a, animal, natural size; b, under view of part of 

 front ; c, outer or third pair of maxillipeds ; d, second maxillipeds ; e, 

 first maxillipeds ; f, outer view of hand ; g, tarsus. 



Puget's Sound, western coast of North America. C. Pickering. 



