. Annual report of the Regents of the University on the condition of the State Cabinet of Natural History, with catalogues of the same. State Cabinet of Natural History (N. Y. ); Science; Museums. No. 109.] 6S subangular along its lateral slopes, closely incurved over that of the opposite valve : dorsal valve much the larger, very prominent in front, obliquely declining towards the beak ; beak depressed, incurved. Surface ornamented by from twenty-five to thirty-three simple subangular plications, seven or eight of which are elevated towards the front of the dorsal valve into a somewhat distin
. Annual report of the Regents of the University on the condition of the State Cabinet of Natural History, with catalogues of the same. State Cabinet of Natural History (N. Y. ); Science; Museums. No. 109.] 6S subangular along its lateral slopes, closely incurved over that of the opposite valve : dorsal valve much the larger, very prominent in front, obliquely declining towards the beak ; beak depressed, incurved. Surface ornamented by from twenty-five to thirty-three simple subangular plications, seven or eight of which are elevated towards the front of the dorsal valve into a somewhat distinct mesial prominence; and from six to eight of those on the middle of the ventral valve are depressed so as to form a broad undefined sinus, which scarcely extends beyond the centre of the valve towards the beak, but is prolonged in front, and abruptly bent upwards nearly at right angles to the dorsal valve into a distinct linguiform extension. The plications are marked in front by the usual longitudinal depressed line along the centre of each, and extremely fine regular zigzag lines corresponding to the sharp interlocking edges of the front and lateral margins of the valves. These fine strige doubtless re- present lines of growth, wliich have become wholly obsolete on other parts of the shell. In this species the two plications bounding the sinus of the ventral valve, and the mesial elevation of the dorsal, sometimes bifurcate towards the beak or middle of the valves, one becoming obsolete on the front. It resembles some of the Bohemian forms which are considered varieties. 1: Rhtnchonella abrupta. 2, 3 : Rhtnchonella Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original State Cabinet of Natural History (N. Y. ); University of the State of New York. Board of Regents. Albany, N. Y. : University of the
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Keywords: ., bookcentury1800, bookdecade1840, booksubjectm, booksubjectscience
