. Bulletin. Natural history; Natuurlijke historie. SPEDEN: THE TYPE FOX HILLS FORMATION 99 130. iioH I- X70 10. -^6 vc9 15 20 25 30 LENGTH IN MM. 35 I 40 âI 45 Fig. 15. Corbicula sp. A. Growth trends of selected specimens, based on measurement of growth lines of large elliptical ( ) and high-oval ( 1. YPM 23875, Loc. 16, A256 6. 2. YPM 23876, Loc. 16, A256 7. 3. YPM 23873, Loc. 16, A256 8. 4. YPM 23874, Loc. 16, A256 9. 5. YPM 23872, Loc. 97, A950 -) specimens. YPM 23878, Loc. 264, A299 YPM 23880, Loc. 264, A299 YPM 23877, Loc. 16, A256 YPM 23879, Loc. 264, A299 â was raised to generic rank by
. Bulletin. Natural history; Natuurlijke historie. SPEDEN: THE TYPE FOX HILLS FORMATION 99 130. iioH I- X70 10. -^6 vc9 15 20 25 30 LENGTH IN MM. 35 I 40 âI 45 Fig. 15. Corbicula sp. A. Growth trends of selected specimens, based on measurement of growth lines of large elliptical ( ) and high-oval ( 1. YPM 23875, Loc. 16, A256 6. 2. YPM 23876, Loc. 16, A256 7. 3. YPM 23873, Loc. 16, A256 8. 4. YPM 23874, Loc. 16, A256 9. 5. YPM 23872, Loc. 97, A950 -) specimens. YPM 23878, Loc. 264, A299 YPM 23880, Loc. 264, A299 YPM 23877, Loc. 16, A256 YPM 23879, Loc. 264, A299 â was raised to generic rank by Cossmann and Peyrot (1911, p. 213). This move is supported by the occurrence of adductor impressions inside the pallial line in Solecardia, whereas they are incorporated in the pallial line in Spaniorinus. Kautsky (1939) states that the genus ranges from Eocene to Recent. It is most common in lower Tertiary sequences. Spaniorinus nicolleti sp. n., described below, differs from typical species in several aspects which are not considered of generic rank. Future work may prove them to be of subgeneric value. The shell is thicker, the muscle scars and pallial line are more im- pressed, the prominent, flat, featureless areas anterior to the cardinal tooth and posterior to the sunken resilifer are not evident on species figured by Cossmann and Peyrot or other workers, the dorsal margin of the right valve tends to overlap and interlock with that of the left valve, and an anterior ridge extends toward the anterior adductor scar from near the umbonal cavity. In spite of careful preparation no small protuber- ance (4b of Cossmann and Peyrot) was observed fused to the posterodorsal part of the cardinal tooth of the left valve. Such a tooth could be easily destroyed. This tooth is not always developed on specimens of the type species (Cossmann and Peyrot, 1911, p. 213). Spaniorinus nicolleti Speden, new species (Plate 21, figs. 14-18; Plate 22, figs. 1-2) Etymology. With reference to it
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