smaller teeth of the same kind. The external form of all these teeth are nearly conical, and within them is a conical cavity, like that within the teeth of many Saurians; their base is fluted, like the base of the teeth of the Ichthyosaurus. Their prodigious size shows the magnitude which Fishes of this family attained at a period so early as that of the Coal formation:[1] their structure coincides entirely with that of the teeth of the living Lepidosteus osseus. (Pl. 27a, Figs. 1, 2, 3.)
Smaller Sauroid Fishes only have been noticed in the
- ↑ We owe the discovery of these very curious teeth, and much valuable information on the Geology of the neighbourhood of Edinburgh, to the zeal and discernment of Dr. Hibbert, in the spring of 1834. The limestone in which these Fishes occur lies near the bottom of the Coal formation, and is loaded with Coprolites, derived apparently from predaceous Fishes. It is abundantly charged also with ferns, and other plants of the coal formation; and with the crustaceous remains of Cypris, a genus known only as an inhabitant of fresh water. These circumstances, and the absence of Corals and Encrinites, and of all species of marine shells, render it probable that this deposite was formed in a freshwater lake, or estuary. It has been recognised in various and distant places, at the bottom of the carboniferous strata near Edinburgh.
In the Transactions of the Royal Society of Edinburgh, Vol. XIII. Dr, Hibbert has published a most interesting description of the recent discoveries made in the limestone of Burdie House, illustrated with engravings, from which the larger teeth in our plate are copied. (Pl. 27, Fig. 11, 12, 13, 14.) The smaller figures, Pl. 27, Fig. 9, and Pl. 27a, Fig. 4, are drawn from specimens belonging to Dr. Hibbert and the Royal Society of Edinburgh.
In this memoir, Dr. Hibbert has also published figures of some curious large scales, found at Burdie House, with the teeth of Megalichthys, and referred by M. Agassiz to that Fish. Similar scales have been noticed in various parts of the Edinburgh Coal field, and also in the Coal formation of Newcastle-on-Tyne. Unique specimens of the heads of two similar Fishes, and part of a body covered with scales, from the Coal field near Leeds, are preserved in the museum of that town.
Sir Philip Grey Egerton has recently discovered scales of the Megalichthys, with teeth and bones of some other Fishes, and also Coprolites, in the Coal formation of Silverdale, near Newcastle-under-Line. These occur in a stratum of shale, containing shells of three species of Unio, with balls of argillaceous iron ore and plants.
