CRUSTACEA. 



pygidium is shorter, the axis being broader and more abruptly elevated, the 



lateral slopes less evenly convex, the pleural annulations more distinct and 

 numerous, the posterior border emarginate. In Proetus Hesione the pygidium is 

 much longer and hears more annulations. 



Distribution. Upper Helderberg group. Schoharie grit: Near Clarksville, 

 Knox and elsewhere, Albany county; Schoharie, Schoharie county. 



Pkoetds Hesione. 



PL VII. XX, FIGS 15, 16. 



Proetus Hesione, Hall. Descr. New S] ies of Fossils, etc., p. 70. 1861. 



Proihis Hesione, Hall. Fifteenth Rept. N. V. state Cab. Nat. Hi I . p 98. 1SH2 

 Proetus Hesione, Hall. Illustrations of Devonian Fossils, pi. x\. figs. 15, 16. 1876. 



Pygidium semi-elliptical, length to width as 2 to 3. Surface axially elevated, 

 depressed-convex on the sides. 



vim relatively narrower than in the associated species of this genus, having 

 a width slightly less than one-third the width of the shield on the anterior 

 margin; longitudinally arched, margins tapering slowly to a rounded, scarcely 

 elevated apex just within the posterior border; composed of ten or eli ven 

 annulations which have a retral curve over the axial line. 



Pleura depressed near the longitudinal furrows, and sloping evenly to the 

 border; composed of eight annulations, each of which is distinctly sulcate for 

 its entire length, and all terminate abruptly at the marginal sulcus. Border 

 broad, evenly sloping, thickened on its inner edge and gently concave. 



Surface faintly pustulose, the pustules heing arranged in rows upon the 

 annulations and scattered irregularly over the border. Length 15 nun., 

 width 21 mm. 



The single pygidium which has served as the type of this species, presents 

 characters so unlike those of the associated species that it will he readily 

 recognized as distinct. From Proetus angustifrons and P. Conradi it differs in its 

 longer pygidium and more numerous annulations. and is in some respects allied 

 to P . planimarginatus, Meek, of the Upper Helderberg limestone of Sylvania, Ohio. 



