. A catalogue of the collection of Cambrian and Silurian fossils contained in the Geological Museum of the University of Cambridge. Paleontology; Paleontology. WEN LOCK GROUP. 145 Case and Column of Drawers. Reference to McCoy's Synopsis: and Figures of Genera. PC Gd2 p. 216. 0. parva, p. 221. Gd Gd Gd2 Gd4 Gc8 p. 220. p. 223. Gc8 Gd Gd Spirifera, p. Gc8 Names and References; Observations, &c. Orthis elegantula, Dalm. (Siluria, 2nd ed. pi. 20, fig. 12. Davidson, Sil. Brach. t. 27, figs. 1—9). Not so common in the Dudley limestone as in the Bala rocks, but still very frequent. I think
. A catalogue of the collection of Cambrian and Silurian fossils contained in the Geological Museum of the University of Cambridge. Paleontology; Paleontology. WEN LOCK GROUP. 145 Case and Column of Drawers. Reference to McCoy's Synopsis: and Figures of Genera. PC Gd2 p. 216. 0. parva, p. 221. Gd Gd Gd2 Gd4 Gc8 p. 220. p. 223. Gc8 Gd Gd Spirifera, p. Gc8 Names and References; Observations, &c. Orthis elegantula, Dalm. (Siluria, 2nd ed. pi. 20, fig. 12. Davidson, Sil. Brach. t. 27, figs. 1—9). Not so common in the Dudley limestone as in the Bala rocks, but still very frequent. I think 0. parva a mere variety, and feel inclined to keep 0. orbicularis distinct. Orthis. var. small and triansrular. 9 o Orthis orbicularis, Sow. (Siluria, 2nd ed. pi. 20, fig. 9). A much rounder and less tri- angular shell than 0. elegantula, but still very closely allied. It is far more common in Ludlow rocks (as at Sedgley), but here and there occurs in true Wenlock; as at Benthall Edge. Orthis hybrida, Sow. (Siluria, 2nd ed. pi. 20, fig. 13. Davidson, Sil. Brach. p. 214). Orthis Lewisii, Davidson (Bull. Soc. Geol. Fr. 2nd. ser. Vol. v. t. 3, fig. 19, Sil. Brach. t. 26, fig. 4). [Orthis porcata, McCoy (see p. 89), is found, though rarely, in the Dudley limestone.] Orthis Bouchardi, Davidson (London Geol. Journ. pi. 13, figs. 5—8; Bull. Soc. Ge"ol. Fr. Vol. V. pi. 3, fig. 19). Orthis biforata, Schloth (De Vern. Geol. Russ. t. 3, Davids., Introduction, pi. 8, fig. 146). Rare in Wenlock rocks: common in Cam- brian rocks:—this' species lingers on, to shew among many others how much closer the relations are between the Upper Cam- brian and the true Silurian strata, than between the former and the lower Cam- brian. Orthis ffiquivalvis, Davidson (Sil. Brach. t. 30, figs. 9, 10; Siluria, 2nd ed. p. 251). Numbers and Localities. a. 753, interior ventral valve; a. 752, interior dor- sal valve; a. 754, mere tri- gonal variety, Dudley, F. C.; b. 769, Erw Gilfach, Builth; a.
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