394 



The Ohio Journal of Scie^ice [Vol. XIX, No. 7, 



In the Calymene which is so abundant in the Waldron 

 shale in western Tennessee, here identified with Calymene 

 hreviceps Raymond (Plate XIX, Fig. 2), described from the 

 Waldron shale of Indiana, the rim of the cephalon extends 

 only for a distance of half a millimeter in front of the anterior 

 margin of the glabella, a narrow but distinct groove intervening. 

 Laterally, the anterior rim of the cephalon widens to about one 

 millimeter. In Calymene celehra Raymond, (Plate XIX, Fig. 4), 

 from the Niagaran of the Chicago district and from the Spring- 

 field limestone of the Eaton quarry, in Ohio, the groove between 

 the anterior margin of the glabella and the anterior rim of the 

 cephalon is deeper, and wider, but the anterior rim is equally 

 narrow. In typical Calymene niagarensis Hall, (Plate XIX, 

 Fig. 1), from the Rochester shale of New York, there is also 

 a narrow furrow separating the glabella from the short anterior 

 rim or "lip" of the cephalon. 



Platycoryphe Gen. Nov. 



In 1898 Pompeckj proposed the genus Synhomalonotus 

 (Neues Jahrbuch Min. Geol. Pal. 1, p. 240), founded on Caly- 

 mene tristani Brongniart. 



Synhomalonotus tristani Brongniart. 



B, enrolled specimen showimg glabella and inverted pygidium. 

 G, lateral view of glabella showing strongly raised anterior lip. 

 (Copied from Brongniart, Hist. Crust. Foss. 1822.) 



The pygidia of this European species resemble that of Calymene 

 whittakeri, figured in this paper (Plate XIX, Fig. 9 B), in the strong 

 backward curvature of the pleural ribs. The median grooves, along 

 the crest of the ribs, do not extend along the entire length of these ribs, 

 but only along their more distal parts. The glabella and the anterior 

 lip are strongly convex from side to side, and although the lateral 

 lobes of the glabella are figured as very oblique, they are at least dis- 

 tinctly defined by deep grooves. 



