PALEONTOLOGIC CONTRIBUTIONS 95 



the anterior angle a small, smooth, semicircular convex area is set 

 off by a groove, from which short, branching, carbonaceous lines 

 radiate on the mould of the interior. From the sides of these areas 

 proceed two transverse grooves halfway to the antero-lateral angles. 



Horizon and locality. Chemung beds, Cotton farm, I mile 

 north of Avoca, Steuben county, N. Y. 



Remarks. This species is easily distinguished from S . e m e r - 

 s o n i by its broader form and the widely open frontal notch. It 

 corresponds in shape to the earliest growth-stages of S . e m e r - 

 s o n i . The test was so thin that in the fossil state it left little 

 more than a carbonaceous film. The grooves and the radiating 

 carbonaceous lines near the frontal edge are features peculiar to 

 this species. The transverse frontal grooves recall those of the 

 aptychus of some ammonites (see text fig. 34). 



Spathiocaris chagrinensis nov. 



Plate 31, figure 5 



Description. Valve of medium to large size, elongate semi- 

 elliptical, not quite one-fourth longer than Avide. Apex situated 

 medially at the anterior margin; from it a smooth, projecting, 

 thickened edge extends toward the anterior angles. The frontal 

 margin, in the compressed condition of the fossil, is slightly 

 emarginate,' the basal margin is strongly rounded and narrow, the 

 widest part of the valve being at the front; the lateral margins 

 extend obliquely forward and were slightly sinuous. The con- 

 centric • growth-lines are rather uniform, closely arranged (8 in 5 

 mm at the posterior extremity), not very prominent. The exfoli- 

 ated portions of the valve show extremely delicate longitudinal 

 lines on the middle part of the valve. 



Measurements. Length 30 mm, width 26 mm. 



Horizon and locality. Chagrin shale (Chemung), Chippewa 

 creek, Breckville, Ohio. 



Remarks. The holotype of this species is in the museum of 

 Western Reserve University, Cleveland, Ohio (no. d 600) and was 

 loaned to us, together with the other species of Spathiocaris, by 

 Prof. H. P. Cushing. 



S. chagrinensis resembles S. emersoni Clarke from 

 the Portage group of New York both in outline and surface char- 

 acters. It also has the fine median longitudinal lines in common 

 with the latter. The wider angle of the frontal cleft in the 

 Chemung species may furnish a distinguishing character. 



