152 CRUSTACEA. 



tero-laterali I0-dentato, dentibus paidulo promiueiitibus, margiiie utri- 

 ttsque postero longissimo et fere recto, subtiliter crenulato, dente pos- 

 tremo triangulate; f route inter-antennali tri-dentato ; articulo anten- 

 narum externarum primo apicem crasse prod,ucto. Pedes antici sub- 

 cequi, manu supra cristatd, multi-dentatd, extus costatd, digito mobili 

 supra denticulate. Pedes 8 postici valde compressi, tarso paido lato, 

 articulis supra granulatis, quarto supra canaliculato, tarso articuloque 

 quinto pedis quinti infra bene ciliatis. Articulus maxillipedis externi 

 tertius oblongus, apicem externum obliqud truncatus. 



Carapax naked, granulate, a little convex, surface somewhat undulate, 

 laterally triangulate, acute, postero-lateral margin nearly straight, 

 antero-lateral ten-toothed, teeth slightly prominent, hinder margin 

 of each very long, and almost straight, and finely crenulate, last 

 tooth triangular; inter-antennary front three-toothed. First joint 

 of outer antennae stoutly produced at apex. Anterior feet sub- 

 equal; hand above cristate and many-toothed, exterior surface cos- 

 tate, moveable finger above denticulate. Eight posterior feet much 

 compressed, tarsus a little broad, joints granulate above, fourth 

 canaliculate above; tarsus and preceding joint of fifth pair promi- 

 nently ciliate below. Third joint of outer maxillipeds oblong, ob- 

 liquely truncate at outer apex. 



Plate 7, fig. 1 a, carapax, natural size; b, part of outer maxilliped; 

 c, hand of small specimen (male), enlarged two diameters; d, extre- 

 mity of posterior legs, enlarged two diameters. 



Bay of San Francisco, C. Pickering, Exp. Exp. 



'Length of carapax, four and three- fourths inches; greatest breadth, 

 seven inches; ratio 1 : 1'47. The areolets are but faintly marked, yet 

 the surface is undulate. 2 M is scarcely at all prominent above the 

 surface either side. In a small specimen the length is thirteen lines ; 

 greatest breadth, nineteen lines; ratio, 1 : 14G. The characters of 

 the anterior legs and the tarsi of the posterior legs are taken from 

 this small specimen. The flattened tarsi and the long ciliation of the 

 inner margin of this and the preceding joint, is a striking character. 

 The outer margin of the third joint of the outer maxillipeds is not 

 long ciliate as in the C. gracilis. 





