siderable doubt exists as to the advisability of creating a new species 

 on the basis of the scanty material at hand which is none too well 

 preserved. The holotype from the Lower Mercer member is evidently 

 compressed; both specimens are in the form of internal casts although 

 a small portion of the shell remains on the smaller. The form is more 

 closely related to L. arata Hall than to any other described species. 

 Comparisons have been made with specimens of the latter species 

 from Missouri with the result that the Ohio species was found to be 

 much larger, probably less convex, more slender, with the posterior 

 portion more extended and the beaks less centrally located. The 

 surface markings are also considerably finer. It can be distinguished 

 from L. bellistriata Stevens by its much larger size, more slender 

 produced posterior extremity, and less centrally placed beaks; from 

 L. meekana Mark by its larger size and still more attenuated form. 



Horizon and locality. Boggs limestone: near Hopewell P.O., 

 Muskingum County (Locality 26), r. Lower Mercer limestone: 

 near Fairview School, Jackson township, Muskingum County, r. 



Leda inflata Girty mss. 

 PL IV, Figs. 17, 18, 19. 



Description. Girty's manuscript description is quoted below. 



"Shell small, rarely exceeding 8 mm. in width, transversely 

 subovate. Basal margin gently convex, slightly sinuate behind, 

 more rapidly curving in front. Anterior extremity rather regularly 

 rounded below the prominent and backwardly turned beaks. Behind 

 the beaks the outline is concave, strongly contracting with the base 

 to form a pointed posterior extremity. Beaks slightly anterior to 

 median line. Convexity high, declining rapidly behind the beaks 

 where a sort of constriction occurs which produces more or less of a 

 sinus in the basal outline and gives the posterior extremity a com- 

 pressed appearance in contrast with the subglobose shape of the major 

 part of the shell. Umbonal ridge high, forming the posterior-superior 

 outline, the post-umbonal slopes being directed almost horizontally, 

 though projecting somewhat at their juncture. 



Surface finely and evenly striated. 



It cannot be said that we know precisely what form the name 

 Leda bellistriata was intended to cover, but from the shells commonly 

 passing as that species L. inflata differs in its smaller size, its more 

 rapidly tapering shape, and its more inflated anterior portion/' 



Remarks. A small species of Leda from the Sharon ore of Ohio 

 is in all probability the same form as that described above by Girty 

 from the Morrow formation of Arkansas. Its association in this 

 State with N .subrotundata and N.lunulata, with which it is also as- 

 sociated in the Morrow formation, helps to strengthen this conclusion. 

 L.inflata is characterized by its small size, its short depressed pos- 

 terior end, and its inflated anterior end. The Ohio form differs in 

 having a somewhat less rapidly tapering posterior end, with less con- 



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