750 THE PALEONTOLOGY OF MINNESOTA. 



[Conoliclias oornutns. 



narrower than it as to effect an abrupt indentation in the ante-lateral margin. Their 

 posterior margin is slightly concave, and from this incurvature the cheeks are made 

 to stand away from the thorax, as in Arges, etc. Their surface is convex and the 

 slope rather the more abrupt on the posterior side. 



Thorax subquadrate, narrowing posteriorly, composed of nine segments, the 

 first of which is obscured. Length of this part (entire), 20 mm.; anterior width 30 

 mm. Axis proportionally broad; on the anterior segments having rather more than 

 one-third the width of the thorax, but relatively narrower behind. Each segment 

 is flat or depressed convex, and there are no nodes or thickenings at their junction 

 with the axial furrow. The axis is regularly convex, and the lateral furrows broad 

 and not deeply impressed. Pleurae flat for about one-third of their width, the outer 

 moiety being evenly deflected. Segments broad, recurved and tapering to acute 

 terminations. 



Pygidium comparatively large, being 17 mm. in length, which is more than one- 

 third the length of the entire animal. Axis very prominent, tapering gradually to a 

 blunt protuberance at about two-thirds of its length, whence the surface becomes 

 abruptly depressed, and the marginal furrows incurve, meeting on the posterior mar- 

 gin. The elevated portion of the axis bears one distinct annulation, and a second one 

 whose posterior groove does not extend to the axial furrows. The ribs of the pleurae 

 are in three pairs. Each is broad, gently convex, the pleural grooves being narrow 

 and sharply incised. Adjoining ribs are united for rather more than one-half their 

 length. The first two pairs are elongate lanceolate, curving backwards. Both of 

 these pairs bear linear grooves on their surface. The members of the third or 

 posterior pair are rhombiform, still with a slight inward curve toward the axial 

 line. 



The surface is covered with fine and coarser tubercles or pustules, which are 

 especially conspicuous upon the pygidium and axis of the thorax. There is no 

 evidence of any other spine upon the test than that rising from the apex of the 

 glabella. 



Formation and locality. Middle Trenton limestone, Trenton Falls, N. Y. 



