Bulletin of the Scientific Laboratories of Denison University (Volume 16) (Paperback)

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1887 edition. Excerpt: ...that of Streblopteria media, but less convex and with a larger posterior ear. Surface marked, as in the opposite valve, by sharp, fine, and very numerous conceritric and radiating striae, the radiating striae becoming very coarse on the anterior. CRENIPECTEN CRENlSTRlATUS, Meek. (Plate V, Fig I4.) A considerable suite of specimens permits little doubt that the various forms of large Pecten-like shells of the upper Waverly all belong in the assemblage named as above by Meek. We have not indeed encountered any individuals with the outline as drawn in the Ohio Palaeontology, but although these figures are not expressly said to be restorations, yet that this is the case is implied in the following remarks: "It is remarkable in having only a comparatively shallow rounded sinus under the anterior ear of the flat right valve, where it is usually deep and angular in species of this genus, while in the left it is deeper and more angular, z'/zoug/z none 0/2'/ze specimens are in a condztzbn to show its exaclform. " Considerable variation is encountered in shells from different horizons. Those found only a few feet above conglomerate II most nearly resemble the figures of Meek, but the left valve has the posterior ear more strongly produced and larger, while the anterior ear is much larger and the margin below the sinus is produced and abrubtly angu lar, instead of gently curved. Specimens from about 100 feet above conglomerate II have much larger posterior ears but otherwise remain nearly the same. The right valve does not usually have the exceptional form referred to by Meek but posseses the usual strong sinus under the anterior ear. The surface of the valve is less strongly marked than the left which is exquisitely ornamented...