g6 CRUSTACEA. 



Subfamily PISINiE. 



Htas ltratus. 



Carapax* lyratus, parce mumte tuberculatus, pone oculos alatZ expands 



marginibm alee antic* posticoque subwquis, paratteUs, margine externa 



excavate, rostra laid, cornubits aeutis, rectis. Bsdes antici siiMUUer 



pubescentes, brachio carpoque margmes pustulatis, manu gracili Rides 



Spostici longi, graciles, suhtilissimd pubescentes. 



Carapax lyrate, sparingly minute tubereulate. behind the eyes alately 

 produced, anterior and posterior margins of the winged expansion 

 nearly equal and parallel, external margin long and a little concave, 

 the anterior angle acute, posterior subacute. Beak smooth, of mo- 

 derate size, horns acute, straight. Anterior feet inconspicuously 

 pubescent, arm and carpus with pustulate margin, hand thin. 

 Eight posterior feet long, slender, very short pubescent, 



Plate 1, tig. 1 a, male, natural size; h t under view of head, enlarged; 

 <\ abdomen, natural size; d, extremity of posterior pair of legs. 



Puget's Sound, C. Pickering, IT. S. Ship Yincennes. 



Near the Myas coarctatus in general form. The margin of the 

 upper surface of the carapax posterior to the alate projection, is small 

 tubereulate in a single series. The posterior margin has a small 

 tubercle at middle. The medial region of the carapax is tumid and 

 crossed by a series of small tubercles, and just behind these a tumid 

 tubercle. The post-medial is prominent and has four or live small 

 pustules, at top, and either side there passes off obliquely backward 

 across the postero-lateral region a line of small tubercles. The pe- 

 duncle of the eyes has a small tubercle on the anterior side. The 

 exterior maxillipecls are granulous or pustulous. The ptervgostomian 

 region has a transverse break in the osseous character of the surface. 

 and is granulous, with the margin entire. Second pair of legs one and 



* The word carapax is not of Latin authority, yet it is so important to the science, 

 that we need make no farther apology for introducing it into that tongue. 



