224 Twenty-fourth Beport on the State Museum. 



the posterior angles of the cheeks. Glabella elevated, broadly sub- 

 conical rounded in front, concave behind ; furrows not visible. 



Eyes comparatively large and prominent, separated from the glabella 

 by a somewhat deep groove ; border of the head broad and flattened. 



Thorax having the axial lobe very prominent, narrower than the 

 lateral lobes ; segments scarcely arching forwards in the middle; 

 lateral lobes geniculate, and having the extremities of the pleura 

 directed backwards and distinctly furrowed to near their outer 

 extremities. 



Pygidium small, semicircular, regularly rounded behind, and the 

 anterior margin straight to near the lateral angles, where it is abruptly 

 curved backwards. Axial lobe narrow, not reaching to the posterior 

 border of the shield ; marked by five small annulations, with about 

 the same number on the lateral lobes, which are less distinctly 

 marked. 



Surface smooth, or very finely granulose. 



This species has no near analogue in any member of the genus 

 hitherto described. It most resembles the P. smiljjtits Barrande, but 

 difi'ers in being destitute of the surface markings and of the furrows 

 on the glabella, and in having ten instead of nine thoracic segments, 

 the extremities of which are pointed backwards, instead of being 

 nearly straight and obtuse as in that species. 



Formation and locality. In shales of the Hudson-river group, 

 Cincinnati, Ohio. 



