98 FIFTEENTH REPORT ON THE CABINET OF NAT. HISTORY. 



and terminate in a scarcely marked furrow, beyond which is a 

 thickened border. 

 Surface very minutely pustulose. 



This species is distinguished by its wide semicircular head, very narrow 

 groove, and wide border. The ribs in the lateral lobes of the pygidium are 

 faintly developed, and sometimes obscure. The minute pustulose markings, 

 when viewed under a lens, have their longest diameter transverse to the 

 axis. 



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

 and in the Helderberg mountains. 



PROETUS ANGUSTIFRONS (n.s.). 



The specimens of this species consist of a part of the head and the 

 pygidium, which, from being associated in the same beds, and from simila- 

 rity of surface-markings, I infer may belong to the same species. The gla- 

 bella is moderately prominent, ovoid, the length and greatest width at base 

 as six to five, and gradually narrowing from the base to the anterior end : 

 the anterior furrow is narrow and not deep, with a wide flat border beyond. 

 The occipital furrow is narrow, and the occipital ring wide and flat upon the 

 top, and abruptly narrowed at each side, with low defined nodes. The pygi- 

 dium is semicircular, very convex ; the axis prominent, broadly rounded, 

 terminating abruptly behind, marked by ten rings ; the lateral lobes marked 

 by six or seven ribs, which are longitudinally grooved : border wide, strong- 

 ly striate on the lower side, and thick. Surface granulose. 



This species differs from the preceding in the narrower and proportionally 

 more elongate glabella ; the border is more flat, and the furrow more gently 

 depressed ; the pygidium is stronger and more convex, and the posterior 

 extremity of the axis more elevated. 



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



PROETUS HESIONE (n.s.). 

 A single specimen of the pygidium, associated with the preceding species 

 in the same rock, presents characters so unlike either of the others, that it 

 must be at once recognized as distinct. 



Pygidium semiellipticalj wider than long, length and breadth about 



as six to eight : axis prominent, a little compressed at the sides 



above the farrow, gradually tapering, marked by about thirteen 



or fourteen rings; those above and below being nearly direct,^ 



while those in the middle, rising vertically from the base, are 



bent backwards above the middle of the sides of the axis, and 



[ September 



