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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1847 Excerpt:...the contiguous volution. Fig. 7 a. View of the back of the shell, showing the strong carina, expanded aperture, and sinus on the dorsal margin, b. Lateral view of the same. Fig. 7 c. Transverse section of the last volution, below the aperture. Fig. 7 d, e. Lateral and front view of another specimen, from which the expanded portion of the aperture is broken off, and showing also a little deviation in form. Position and locality. In the lower irregularly bedded portions of the Trenton limestone, and in the strata resting on the Black-river limestone, at Watertown, Jefferson county. (State Collection.) 244. 4. BUCANIA BIDORSATA (n. sp.). Pl. XL. Figs. 8 a, b, c, d, e,f, g. Convolute, subglobose, with a deep umbilicus; volutions about three, the last one extended and somewhat straight, gradually enlarging and more abruptly expanding towards the aperture; dorsal margin with a double or grooved carina, on the centre of which is a narrow elevated line; on each side of the dorsal band is a broad groove or depression, and an obtusely angular ridge, the latter being half way between the centre and margin of the shell; surface ornamented by transverse filiform stria;, which, receding from the umbilicus, bend abruptly backwards near the centre, making a more gentle curve on the dorsal band; aperture sublunate. In young specimens, the carinal band is very conspicuous, with a narrow elevated central line. The lateral carina or ridges scarcely affect the direction of the striae; the depressions on the outside of these are less conspicuous than on the inner side. In this respect, however, there is some variation in specimens from different localities. In casts of the shell, the detail of the surface markings is partially lost, and a broad dorsal carina is sometimes all tha...