. Report upon the palaeontology of the province of Ontario [microform]. Paleontology; Paléontologie. m iiii ni; 78 91. Chonetes arcuata (Hall). Chonetes arcuata (Hall), Tenth Report on the State Cabinet, 116, Chonetes arcuata (Hall), Pal. New York. Vol. IV., Plate XX., Fig. 7. Shell semi-elliptical, or nearly scmi-ciroular; the hin-jje line equal to, or slightly longer than, the greatest width of the Hhell; the cardinal angles produced into distinct ears, which, however, are usually short and compresned. Ventral valve extremely convex or ventricose, often with a shallow longitudinal depres- si
. Report upon the palaeontology of the province of Ontario [microform]. Paleontology; Paléontologie. m iiii ni; 78 91. Chonetes arcuata (Hall). Chonetes arcuata (Hall), Tenth Report on the State Cabinet, 116, Chonetes arcuata (Hall), Pal. New York. Vol. IV., Plate XX., Fig. 7. Shell semi-elliptical, or nearly scmi-ciroular; the hin-jje line equal to, or slightly longer than, the greatest width of the Hhell; the cardinal angles produced into distinct ears, which, however, are usually short and compresned. Ventral valve extremely convex or ventricose, often with a shallow longitudinal depres- sion, extending from the umbo to near the middle of the shell. Beak prominent and in- curved ; hinge-line supporting ten to twelve tubular spines, which are directed obliquely out- wards, and are rarely preserved. Dorsal valve deeply concave, following the convexity of the ventral valve. Surface marked by fine rounded striae, which both bifurcate and increase by interstitial addition. From six to seven striaj occupy the space of one line, and the intervals between them are not only narrower than the width of the ribs themselves, but often have the charac- ter, especially in partially exfoliated specimens, rather of rows of elongated pits than of ex- tinct grooves. This species is very closely allied to C. hemispherica in its form and general character. It is readily distinguished from the latter by its much more numerous and finer striae. Locality and Fmmation.—Not uncommon in the Corniferous Limestone of Port Colboriif. 92.—ClIONETKS ACUTI-RADIATA (Hall), Strophomena acuti-radiata (UnW), Geol. Report, 4th Dist., New York, p. 171, Chonetes acuti-radiata (Hall), Tenth Reiiort on the State Cabinet, p. 117. Chonetes acuti-radiata (Hall), Pal. , Vol. IV., Plate XX., Fig. 5. Shell semi-elliptical, it width along the hinge-line nearly or more than twice as great a» its length ; cardinal angles produced. Ventral valve convex, but not excessively so, depressed towards the flatt
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