. A catalogue of the collection of Cambrian and Silurian fossils contained in the Geological Museum of the University of Cambridge. Paleontology; Paleontology. Operculum of Maclurea. p. 312. G. G Gk5 Cfirtoceras. p. 314. I 0. subundulatum, p. 317 Names and References; Observations, &c. Euomphalus, sp. Eccyliomphalus? scoticus, McCoy. The true Eccyliomphalus of Portlock is a Pteropod; this may be Phanerotinus of Sowerby. Heteropoda. Blaiuville {Nucleolranchiata, Rang). All or most living forms of this group are thin light shells; but there seems much reason for Dr. Woodward's opinion, that
. A catalogue of the collection of Cambrian and Silurian fossils contained in the Geological Museum of the University of Cambridge. Paleontology; Paleontology. Operculum of Maclurea. p. 312. G. G Gk5 Cfirtoceras. p. 314. I 0. subundulatum, p. 317 Names and References; Observations, &c. Euomphalus, sp. Eccyliomphalus? scoticus, McCoy. The true Eccyliomphalus of Portlock is a Pteropod; this may be Phanerotinus of Sowerby. Heteropoda. Blaiuville {Nucleolranchiata, Rang). All or most living forms of this group are thin light shells; but there seems much reason for Dr. Woodward's opinion, that the heavy Bellerophon andMaclweawere solid representatives of this low order of Molluscs. Maclurea Logani, Salter (Geol. Survey, Canada Decade I. pi. 1). The proportions of the mouth and whorls of this massive shell agree better with M. Logani than the great M. magna of the Chazy limestone. Cephalopoda, Cuvier. The tetrabranchiate fami- lies (only) are known in Palaeozoic rocks— and Nautiloid and Orthoceras-like forms are among the very earliest known Molluscs, except Pteropoda and Brachiopoda. They are particularly abundant in the representa- tives of the Llandeilo flag or Lower Bala groups. Cyrtoceras multicameratum, Hall. Hall's sp. is from Trenton limestone, which represents Middle Bala. Many forms migrated in Cambrian times eastward from America, and are consequently of older date there than in Britain. But few follow a reverse order of progression. Orthoceras (centrale, Hisinger?), Leth. Suec. t. 9, fig. 4. Not likely to be Hisinger's Swedish species. Orthoceras fluctuatum, Salter, Coarser striae than 0. subundulatum, Portl. and apparently more bent still than in that species. Numbers and Localities. S. W. of Pwllheli (Mid. Bala?) a. 91, Knockdollian, Ayr- shire. a. 89, Colmonel, Stinchar River, Ayrshire. It also occurs at Bugon, and other Ayrshire localities. a. 88, Knockdollian Mt., 3 miles from Ballintrae, Ayrshire. a. 87, Llandeilo. a. 611, Wellfield, Builth,
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