DESCRIPTION OF SPECIES 241 



two related species differing chiefly in size may exist; and if the char- 

 acters exhibited in his figure prove constant in a number of specimens, 

 a different species rather than an abnormal development of P. tropi- 

 dophorus is represented. This form differs not only in its larger size, 

 but in its less angular posterior outline and its convex ventral margin. 

 Collections were made from a number of localities along Flint Ridge, 

 but no specimens comparable to Herrick's large form were discovered. 

 Horizon and locality. Lowellville member: Muskingum County, 

 Locality 19, r. Common and widely distributed in the Lower Mercer 

 and McArthur members. Upper Mercer limestone : Muskingum County, 

 Locality 68, r. Black Flint member: Jackson County, Locality 87, r. 



Astartella compacta Girty 



1915 Astartella compacta. Girty, Missouri Bureau Geal. and Mine?, Per. 2, Vol. XIII, 

 p. 354, PI. XXVIII, Figs. 4, 4a, 5, 5a. 

 Cherokee formation: Missouri. 



Description. This species is represented in the collections studied 

 by a number of specimens from the Lower Mercer and McArthur 

 members in a fairly good state of preservation; they exhibit no essential 

 differences from the Missouri forms. The species is distinguished by 

 its small compact form with the height a little greater than the length, 

 by its high, slightly flaring posterior end, and by its surface sculpture 

 of fine, very closely arranged concentric lines. 



Horizon and locality. Lower Mercer limestone: Perry County, 

 Locality 35, r; Muskingum County, Locality 28, c; Licking County, 

 46, r. McArthur limestone: Jackson County, Locality 80, r; Vinton 

 County, Locality 84, c; Hocking County, Locality 86, r. 



Astartella concentrica (Conrad) 

 PI. XIII, figs. 11-13 



1842 Nuculites concentrica. Conrad, Acad. Nat. Sci. Phil. Jour., 1st Ser., Vol. 8, 



Pt. 2, p. 248. 



Coal Measures: Pennsylvania. 

 1915 Astartella concentrica. Girty, U. S. Geol. Surv., Bull. 544, p. 142, Vol. XVIII, 



Figs. 2-9. 



Wewoka formation : Oklahoma. 



Description. Two closely related representatives of the genus 

 Astartella are common in the middle and upper Pottsville formation, 

 one of which has been referred to A. concentrica and the other to the 

 form which Meek called A. newberryi. Conrad's original description of 

 A. concentrica is quoted below: "Subtriangular, slightly ventricose, with 

 rather distant sharp concentric striae; umbonal slope obtusely angu- 



