[24 PALAEONTOLOGY OF NEW YORK. 



cops rana and Dalmanites Boothi, var. Calliteles, as does also P. Rnwi, in the basal 

 layers of the Hamilton shales. 



The name Proehts marginalis, Conrad, as far as it has included the forms 

 of Pro, his occurring in the Tally limestone, may therefore be regarded as 

 synonymous with P. Rowi, Green. 



Distribution. Hamilton group. In the Hamilton shales: On Seaver's Creek, 

 Township of Canandaigua, Ontario county; York, Livingston county; Ham- 

 burgh and Eighteen-mile creek, Erie county; Vly creek and elsewhere, Otsego 

 countv. In the sandy shales of Schoharie county. In the Tully limestone : 

 Below Lodi Landing, Seneca lake; at Weston's quarry, near Spofford Corners, 

 Split Rock, near Borodino, and Tully, Onondaga county; Moravia, Cayuga 

 county, and Cuyler, Cortland county. 



Proetus jejunus, n. sp. 



PLATE XXV, FIG. 7. 



l'viiiuiUM moderately large, the posterior outline being the arc of a circle. 

 . Axis elevated, relatively narrow, having one-fourth the width of the shield 

 on the anterior margin ; tapering rapidly to an obtuse apex distant from the 

 posterior extremity. The apex is slightly elevated, a low, depressed ridge 

 connecting it with the posterior border. Ten annulations can be counted, 

 all of which show a retral bend over the axial line, and each bears a con- 

 spicuous central node. 



The pleura are relatively broad and slope with a gentle curve outward to 

 the narrow border. There are eight annulations, exclusive of the articulat- 

 ing ring, and on the cast of the lower surface they appear to have been 

 distinctly sulcate. Border smooth except near the antero-lateral angles, 

 where it is encroached upon by the annulations. 



dimensions. Length 13 mm., width 21 mm. 



Observations. This species is represented by a single pygidium from which 

 the crust has been largely removed, hut the specimen is sufficient to show that 



