DESCRIPTIONS OF SPECIES. 307 



STEEBLOPTERIA McCoy, 1851. 



SXEKBLOPTEKIA MEDIA. 



PL I, fig. 13. 



1888. Streblopteria media. Herrick, Sci. Lab. Denison Univ., Bull., vol. 3, p. 56, pi. 3, figs. 4, 8, 9; 



pi. 1, figs. 13, 19; pi. 7, figs. 2, 6. 

 Waverly group : Licking County, Ohio. 

 1895. Streblopteria media. Herrick, Geol. Surv. Ohio, Rept., vol. 7, pi. 24, figs. 16, 17. 



Cuyahoga shale: Moots Run, Ohio. 



From the Millsap limestone of Perry Park was obtained a single specimen of a 

 pectinoid shell which so closely resembles Herrick's description and figures of St, 

 media that the identification with that species is made with some confidence. The 

 shape, which is well shown by the illustration, agrees very closely with the right 

 valve figured by Herrick as fig. 8 of pi. 3. The chief points of difference which I 

 have been able to detect are not important. Possibly the posterior wing of my speci- 

 men is a trifle larger, and the outline under the anterior wing does not project as it 

 is seen to do in Herrick's figure, but more nearly approaches a straight line. The 

 surface appears to be almost smooth, being interrupted only bj^ obscure concentric 

 lines and corrugations. The anterior wing, however, has a few coarse, indistinct, 

 radiating striae. 



Locality and horizon. — Castle Rock quadrangle (station 2389); Millsap limestone. 



MYALINA de Koninck, ISM. 



Mtalina areansasana Weller?. 



1897. Myalina arhansanu. AVeller, New York Acad. Sci., Trans., vol. 16, p. 262, jil. 19, figs. 16, 17. 

 (Date of volume, 1898. ) 

 Batesville sandstone: Batesville, Ark. 



This species has been identified in the San Juan, Canyon, and Leadville districts, 

 in Colorado, and a form believed to be the same occurs in the limestones of St. 

 Louis age at Pella, Marion County, Iowa. The Colorado material upon which the 

 following brief description is based is in every case preserved in a cherty matrix; 

 it is often obscure and unfavorable for study. 



The shape is mqdioliform. The axis is oblique, and there is a distinct anterior 

 lobe. The posterior outline is entire and subrectilinear. The anterior extremity is 

 rounded; the posterior-superior angle obtuse and not projecting in an alate or 

 mucronate extension. The surface appears for the most part nearly smooth, though 

 obscure, ill-defined, concentric markings can be made out. Toward the anterior end. 

 however, these gradually become stronger and develop into sharp, regularl}^ spaced 

 ridges. 



