. A catalogue of the collection of Cambrian and Silurian fossils contained in the Geological Museum of the University of Cambridge. Paleontology; Paleontology. 18 MIDDLE CAMBRIAN. Case and Column of Drawers Keference to McCoy's Synopsis: and Figures of Genera. G case G case G case Gi G case Gi G case and Gi. Names and Eeferences; Observations, &c Numbers and Localities. Theca (Centrotbeca) cuspidata, Salter (Mem. Geol. Surv. Vol. m. pi. 10, fig. 25). A long horn projects on each side from the mouth. Theca trilineata, MSS. A small species with longitudinal lines. Conularia Homfrayi, Salter
. A catalogue of the collection of Cambrian and Silurian fossils contained in the Geological Museum of the University of Cambridge. Paleontology; Paleontology. 18 MIDDLE CAMBRIAN. Case and Column of Drawers Keference to McCoy's Synopsis: and Figures of Genera. G case G case G case Gi G case Gi G case and Gi. Names and Eeferences; Observations, &c Numbers and Localities. Theca (Centrotbeca) cuspidata, Salter (Mem. Geol. Surv. Vol. m. pi. 10, fig. 25). A long horn projects on each side from the mouth. Theca trilineata, MSS. A small species with longitudinal lines. Conularia Homfrayi, Salter (Mem. Geol. Surv. Vol. in. pi. 10, figs. 11—13). A very large species, so slightly calcareous as to appear mere membrane on the slate. The pucker- ing of the surface is probably due to unequal contraction. See Lower Ludlow Rocks. Bellerophon arfonensis, Salter (1. c. p. 349, pi. 10, figs. 6—8). Squamose lines of growth, remote and rather regular. Bellerophon multistriatus, Salter (1. c. p. 350, pi. 10, figs. 9,10). With close decussating striae. b. 336, Portmadoc. (Mr. Homfray.) b. 333, Moel-y-gest, base of Upper Tremadoc. (Mr. Homfray.) Garth, Portmadoc. (Mr. Ash.) b. 323, 324, 325 figured specimens in abov< work. (Mr. Homfray.) Garth, Portmadoc. b. 328. 341 (Mr. Homfray, figured specimens). Garth, Portmadoc. (Mr. Homfray.) Garth, Portmadoc. (Pre- sented by Mr. Salter.) b. 321, 322, figured speci- mens in the work quoted. (Mr. Homfray.) CEPHALOPODA. Orthoceras sericeum, Salter (1. c. Vol. in. p. 356, pi. 10, figs. 4, 5). This, and the Gyrtoceras prcecox of the same work, are the oldest known forms of the Nautiloid, or shelly Cephalopod group. Cephalopoda became abundant in the succeeding period—the Baia group, even in its lower portion : and a few are known in the Arenig Group, b. 321 shews the septa. The great break, in organic life, between the 'Tremadoc Slate' and the 'Arenig or Skiddaw Group,' has disposed me, ever since I worked out their respective faunas in the
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