. A catalogue of the collection of Cambrian and Silurian fossils contained in the Geological Museum of the University of Cambridge. Paleontology; Paleontology. Isotelus. PI. 1 F, tig. 3, p. 169. Labrum of Univalve Shells. Pteropods. Names and References; Observations, &c. Numbers and Localities. TRILOBITA. Angelina Sedgwickii, Salter (Decade Geo! Surv. 11. pi. 7). The most abundant of the Tre- madoc trilobites : allied to Olenus, but with 15 body rings {Olenus has 14), and greatly larger than any known species of that genus. Even size is a character of some importance in classific
. A catalogue of the collection of Cambrian and Silurian fossils contained in the Geological Museum of the University of Cambridge. Paleontology; Paleontology. Isotelus. PI. 1 F, tig. 3, p. 169. Labrum of Univalve Shells. Pteropods. Names and References; Observations, &c. Numbers and Localities. TRILOBITA. Angelina Sedgwickii, Salter (Decade Geo! Surv. 11. pi. 7). The most abundant of the Tre- madoc trilobites : allied to Olenus, but with 15 body rings {Olenus has 14), and greatly larger than any known species of that genus. Even size is a character of some importance in classification. Occurs in all sorts of com- pressed shapes in the slate and sandstone. Dicellocephalus furca, Salter (Mem. Geol. Surv. Vol. in. pi. 8, fig. 9, 10). Belongs to the section Centropleura (ib. p. 303). Asaphus (Isotelus?) affinis, McCoy. Perhaps distinct from the following species. The facial suture is marginal in front. Asaphus () Homfrayi, Salter (Mem. Geol. Surv. Vol. in. p. 311, pi. 8, fig. 11—14). The earliest known form of this genus in Britain, if indeed the entire form of the labrum do not prove it a distinct genus nearer Ogygia. (See Lower Bala.) b. 344 is the labrum. The subgenus Isotelus is uncertain here, for the labrum is not notched as in that form. Ogygia scutatrix, Salter (Mem. Geol. Surv. Vol. III. p. 312, pi. 8, f. 8, pi. 9, fig. 1). 8 or 9 inches in diameter, and nearly round. More like the French species from Brittany, maresti. Cheirurus Frederici, Salter (Mem. Geol. Surv. Vol. in. p. 322, pi. 8, figs. 1—3). A species with a general resemblance to the G. (Ec- coptochile) Sedgwickii, McCoy (see Lower Bala), but with spines to the hinder rings of the body. PTER0P0DA AND HETER0P0DA. Theca simplex, Salter ? (Mem. Geol. Surv. Vol. in. p. 352, pi. 11 b, fig. 22—26). This, if the same as the Arenig group species, is the only fossil common to both formations. In Canada there may be a transition from the Primordial Group to the Upper Cambrian, o
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