Professor Emerson on HalVs Geological Collections. ' 583 



Trilobites sp. 



I liiiv(3 figured a small pygidiiun, Avliicli is lnoad and flattoned, apparently 

 acutely terminated behind, witli tliickeued lim, and Itioad, Aery slightly elevated 

 ribs. 



In black limestone. 



Fio;. 10, magnified soveu times. 



Cyphaspis % Frobtsheri, n. s. 



The only parts certainly belonging to this species are the impressions of 

 two cheeks upon different cleavage faces of a piece of the black limestone 

 with Triartlirus BecJcii, unless a pygidium upon the same piece, 

 which agrees well with that of Cyphaspis Burmeisteri, Bar., in 

 shape, may belong to the same individual. The cheek is thin, 

 flattened, smooth, very remarkable for its angular outline 

 and the very abnormal curvature of the spine. The edge is Fig. ii, magnified 

 separated from the rest of the cheek by a deep groove, flat at j frtiiofciieck 

 the bottom, broad in front, and narrowing behind. The border is 13 mm. 

 formed by the curving upward of the crust and not by its thickening, and the 

 spine is a prolongation of this border, having for a time the same dimensions and 

 ending abruptly. The suture starts from a point on one side of the central line 

 and runs across the border, directed towards the central point of the glabella, 

 then continues in a sigmoid curve to the eye, and running around that passes in 

 a curve outwardly convex to meet the posterior of the head at a point just inside 

 the base of the spine. The eye shows mark«s of six facets placed in one curved 

 line. 



In black limestone — Utica slate. 



