66 PALEONTOLOGY OF NEW YORK. 



The pleura are moderately broad and bear eleven or twelve low and flat 

 annulations, which are grooved by fine impressed lines, and become obsolete 

 upon the wide and slightly thickened border. 



Htpostoma. Elongate, sub-triangular; width on the anterior margin equal 

 i.) the length. Anterolateral angles broadly auriculate ; lateral margins 

 incurved and rapidly approximating. The posterior margin apparently bears 

 five minute spines, one situated medially, and two on either side, but the only 

 specimen observed is somewhat broken at this part, and its character cannot 

 be satisfactorily determined. Margins thickened and sharply deflected. 

 Cntrum low, depressed-convex. Posterior sulcus conspicuous; postero- 

 lateral pits moderately strong and elongate. 



Surface Ornamentation. The glabella is covered with moderately strong 

 and evenly disposed tubercles which become obscure or obsolete upon the 

 cheeks and margin. The frontal lobe of the glabella bears a circular pit on 

 the axial line just back of its centre. The segments of the thorax appear 

 faintly pustulosc upon the axis; otherwise the surface is smooth or minutely 

 granulose. 



Dimensions. The single entire individual known measures as follows. 



Body. Cephalon. Thorax. Pygidium. Hypostoma. 



Length 80 mm. 23 mm. 32 mm. 25 mm. 18 mm. 



Width 44 mm. 44 mm. 41mm. 30 mm. 18 mm. 



Observations. The pygidium of Dalmanites Calypso shows strong points of 

 similarity with that of D. Erina. They differ, however, in these respects: (a) 

 the type of D. Erina is faintly nodose along the axial line, but not angulate or 

 spinose, (b) the shield is more depressed, (c) the outline is a broader curve, and 

 (d) the border wider and usually somewhat unsymmetrical It may eventually 

 become necessary, with a more complete knowledge of the latter species, to 

 unite the two under on<' designation, but with our present material is seems 

 rable to retain the species tentatively as distinct, 



Distribution. Upper Helderberg -roup. Corniferous limestone: Sandusky. 

 Ohio: Falls of the Ohio, Ky.; Schoharie, N. Y. 



