128 Cincinnati Society of Natural History 



numerous on the inner layers of the shell, and here, also, the 

 radiating striations, obscure or obsolete on the surface, are 

 distinct. Fig. 2 represents the typical form from the Fairmount 

 at Cincinnati. Fig. 3 is the Rogers Gap specimen. 



Shells of the cincinnatiensis type begin their range in the Tren- 

 ton of. New York, from which they were identified by 

 Hall as Lingula quadrata, an incorrect determination. In 

 the specimen figured in Dana's Manual (p. 507, Fig. 667), the 

 outer shell layer is black, and concentrically striated. The inner 

 shell layer is white, and marked by numerous radiating lines, es- 

 pecialy along the middle part of the shell. The concrete laterals 

 are gently convex as in Lingula cincinnatiensis. The anterior mar- 

 gin is rounded rather than quadrate. Lingula rectilateralis, Em- 

 mons, was figured among a group of fossils regarded as of Utica 

 age because associated with Triartlirus. Of this group of "Utica" 

 fossils, probably only Avicula insucta was figured from the Mo- 

 hawk valley. Hall figured as Lingula rectilateralis a specimen 

 from the vicinity of Lorraine. The anterior margin is rounded 

 rather than quadrate. Radiating striae are distinct along the middle 

 part of the shell, becoming finer beyond lines drawn from the 

 beak to the antero-lateral margins. Apparently there was a strong 

 median septum, anterior to cuneiform concrete laterals, the an- 

 terior part of the inner pair corresponding to the central scars, 

 as in Lingula cincinnatiensis, but the curvature of these concrete 

 lateral scars appears to have been concave, the shell being very 

 thin. Lingula ioivaensis, Owen, from the Maquoketa of the North- 

 west, also is figured as having concave concrete laterals, but in all 

 other respects resembles Lingula cincinnatiensis, although usually 

 figured as having a more quadrate outline. This group of shells 

 is so closely related that it will require an abundance of speci- 

 mens to discriminate the different species. Lingula cincinnatien- 

 sis was described from the Fairmount member of the Maysville 

 at Cincinnati, Ohio. 



11 — Lingula zvhitfieldi, Ulrich. (Plate II. Fig. 8.) — A broadly 

 oval brachial valve, 21 mm. in length and 17 mm. in width, agree- 

 ing in outline with the published figure of Lingula zvhitfieldi, was 



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