. A catalogue of the collection of Cambrian and Silurian fossils contained in the Geological Museum of the University of Cambridge. Paleontology; Paleontology. MIDDLE BALA GROUP. 55 Cnse and Column of Drawers. Reference to McCoy's Synopsis: and Figures of Genera. Gl Ling. Davisii, in part. PI. 1 L, fig. 6. PL 1 L, fig. 8, p. 254. Gl Gl p. 253. Pseudoorania, p. 187. PL 1 h, figs. 1, 2. do. Gl Sjririgerina, p. Names and References; Observations, &c. Lingula, Bruguiere. The true Lingulce appear to have commenced existence in the Bala rocks; as the Lmgulellce are characteristic of the Mi
. A catalogue of the collection of Cambrian and Silurian fossils contained in the Geological Museum of the University of Cambridge. Paleontology; Paleontology. MIDDLE BALA GROUP. 55 Cnse and Column of Drawers. Reference to McCoy's Synopsis: and Figures of Genera. Gl Ling. Davisii, in part. PI. 1 L, fig. 6. PL 1 L, fig. 8, p. 254. Gl Gl p. 253. Pseudoorania, p. 187. PL 1 h, figs. 1, 2. do. Gl Sjririgerina, p. Names and References; Observations, &c. Lingula, Bruguiere. The true Lingulce appear to have commenced existence in the Bala rocks; as the Lmgulellce are characteristic of the Middle Cambrian or Lingula Beds. Lingula is the most equivalve, and least complex of all the genera of Brachiopods, the muscles widely separated, the shell is horny and flexible, without calcareous mat- ter or any hinge. The spiral arms are fleshy only. No calcareous spires occur in palaeozoic rocks till we reach the Devonian and Carboniferous periods. ? Lingula ovata*, McCoy (Davidson, Mon. Sil. Brach. p. 38, pi. 2, figs. 19—23). [The spe- cimen figured is a squeezed specimen of L. Davisii from the true Lingula flags, p. 39.] Lingula tenuigranulata, McCoy (Davidson, Sil. Brach. p. 37, pi. 2, figs. 9—14). One of the largest species known in any rock. Lingula longissima, Pander, Beitrage, pi. 3, Dav. Sil. Brach. pi. 3, figs. 28—30. Numbers and Localities. fig- 21. Crania divaricata, McCoy (Davidson, Mon. Sil. Brach. pi. 8, figs. 7—12). The genus Crania is world-wide from the Bala beds to the present day. Trematis (Discina) corona, MSS. A giant spe- cies. The genus differs from Discina by its marginal foramen for the byssus. T. punctata Sow. (Dav. Sil. Brach. pi. 6, fig. 9). Atrypa marginalis, Dalm. (Siluria, 2nd ed. pi. 22, fig. 19). A common fossil in beds above the Bala limestone; more rare in N. Wales and Ireland. No hinge line—but calcareous spires placed so that the spire lies flat in the valve—mark this genus. b. 202, Coniston (as L. Davisii) ; Bryn Melyn, Bala,
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