CONTRIBUTIONS TO PALEONTOLOGY. 99 



make a slight retral curve on the summit. The lateral ' ' ^s are 

 marked by nine ribs, which are deeply grooved along the middle, 

 and more sharply marked in the cast. The ribs terminate on the 

 border in a distinct groove, the outer side of which is nearly flat; 

 thence bending abruptly downwards, and a little spreading at the 

 margin, making the border gently concave. 

 Surface unequally pustulose; the pustules on the ribs of the pygi- 

 dium arranged in rows on each side of the groove, and distinctly 

 marked in the cast. 



This species will be readily distinguished from the preceding by its form 

 and the distinctness of the ribs in the lateral lobes, and more distinct groove 

 along the centre, as well as stronger pustules. 



Geological formation and locality. In the Schoharie grit at Schoharie. 



PROETUS CLARUS ( n. s.). 

 Body very convex, elliptical; width two-thirds as great as length. 

 Head ver}^ convex, nearly semicircular; length a little greater 

 than half the width; the anterior and sides limited by a border 

 of moderate width with a narrow furrow, beyond which it is al- 

 most flat for more than half the width, then slopes suddenly to 

 the margin. In the cast the furrow becomes wider, and is limited 

 by a narrow rounded ridge, beyond which the surface is concave 

 to the outer margin. The border is prolonged posteriorly into 

 spine-like processes, extending to about the fourth articulation. 

 Glabella very prominent, round-ovoid; length equal to the width 

 at base, gently narrowing and rounded in front : the occipital 

 furrow narrow, with a strong occipital ring. Eyes prominent, two- 

 thirds as high as long. 



In the thorax, the axis is prominent, semicircular in profile, the 

 annulations direct : the lateral lobes are nearly flat for one-third 

 their width, and then bend at an obtuse angle along the line of the 

 geniculation of the ribs. Ribs sharply grooved a little anterior to 

 the middle : the salient anterior portion of the rib rests against the 

 posterior margin of the next anterior rib, which is distinctly bent 

 backwards at this point. 



The pygidium is semicircular; the axis very prominent, with nine 

 or ten rings : the lateral lobes are a little flattened near the axis, 

 and slope abruptly to the margin. Five or six ribs may be counted, 

 which are marked by a shallow longitudinal groove, but are simple 

 1861.] 



