THE MTRIAPODA OF NORTH AMERICA. 227 



anterior. The head is bright-chestnut, and is ornamented with a median furrow 



Fio\ 57 



on its vertex, and a pair of impressed dots on eacli side of its face. Its inferior 

 border is medianly moderately emarginate. The margins of the side plates are 

 somewhat thickened. The anal scutum is yellowish, small, subtriangular, and 

 distinctly emarginate posteriorly. The feet are very slender, and are shortly 

 pilose. The femora of the hinder ones are armed each with a small spine on their 

 distal extremity. The small male appendages are hairy at the base. They are armed 

 with a broad, obtuse, spinous process, and a slender curved spine besides the terminal. 

 The latter is robust, and is bent with a double curve, that is, anteriorly and laterally. 

 I have dedicated this species to my friend, Dr. Hayden, whose name is inseparably con- 

 nected with the natural history of the Far West. 



Hah. Oregon. — Museum of the Smithsonian. 



Subgenus STRONGYLOSOMA. 

 Corpus cylindricum. Laminae laterales subnullee. 

 Body cylindrical. Lateral laminae very small. 



- 



P. ERUCA. 



P. brunneus ? robustus ; antennis brevibus, pilosis, haud clavatis ; scutis subrude punctatis ; pedibus pavvis, 

 gracilibus, modice hirsutis. 



Brown ? robust; antennas short, pilose, not clavate; scuta subrudely punctate; feet small, slender, moderately 

 hirsute. 



P. eruca, Wood, Proc. Acad. Nat. Sci., 1864, p. 8. 



Judging from the badly preserved alcoholic specimens, the color of this species is red- 

 dish-brown, with the side plates a lighter color. The body is very robust. The head lias 

 a median furrow on its vertex, and its lower border emarginate. The side plates, ex- 

 cepting the posterior, which are better pronounced, have but the posterior angles, which 

 are acute. The scuta appear to have a narrow edging of black posteriorly. The terminal 

 scutum is subtriangular, very prolonged and very thick posteriorly. I have never had 

 an opportunity of examining the male organs. Those of the female are very pilose, and 

 are formed of two portions. They are contracted at their bases, and expanded above, 

 somewhat as a reversed flattened cone. The basal piece is thicker and less hairy than 

 the other. The distal piece is set into it, and lias an opening along the free extremity. 



Hub. Oregon. — Museum of the Smithsonian. 



