Lower white chalk without flints.
Upper green-sand.
Gault.
Lower green-sand and Kentish rag.
The best known and most characteristic large extinct animal of the chalk formations is chiefly found in the uppermost and most recent division, and is called
No. 1.—The Mosasaurus.
(Mosasaurus Hoffmanni, Hoffmann’s Mosasaur.)
Of this animal almost the entire skull has been discovered, but not sufficient of the rest of the skeleton to guide to a complete restoration of the animal. The head only, therefore, is shown, of the natural size, at the left extremity of the Secondary Island.
The first or generic name of this animal is derived from the locality, Maestricht, on the river Meuse (Lat. Mosa), in Germany, where its remains have been chiefly discovered, and from the Greek word sauros, a lizard, to which tribe of animals it belongs. Its second name refers to its discoverer, Dr. Hoffmann, of Maestricht, surgeon to the forces quartered in that town in 1780. This gentleman had occupied his leisure by the collection of the fossils from the quarries which were then worked to a great extent at Maestricht for a kind of yellowish stone of a chalky nature, and belonging to the most recent of the secondary class of formations in geology. In one of the great subterraneous quarries or galleries, about five hundred paces from the entrance, and ninety feet below the surface, the quarrymen exposed part of the skull of the Mosasaurus, in a block of stone which they were engaged in detaching. On this discovery they suspended their work, and went to inform Dr. Hoffmann, who, on arriving at the spot, directed the operations of the men, so that they worked out the block without injury to the fossil; and the doctor then, with his own hands, cleared away the matrix and exposed the jaws and teeth, casts of which are shown in the cretaceous rock of the Island.
This fine specimen, which Hoffmann had added with so much pains and care to his collection, soon, however, became a source of chagrin to him. One of the canons of the cathedral at Maestricht, who owned the surface of the soil beneath which was the quarry whence the fossil had been obtained, when the fame of the specimen reached him, pleaded certain feudal rights to it. Hoffmann resisted, and the canon went to law. The Chapter supported the canon, and the decree ultimately went against the poor surgeon, who lost both his specimen and his money—being made to pay the costs of the action. The canon did not, however, long enjoy possession of the unique specimen. When the French army bombarded Maestricht in 1795, directions were given to spare the suburb in which the famous fossil was known to be preserved; and after the capitulation of the town it was seized and borne off in triumph. The specimen has since remained in the museum of the Garden of Plants at Paris.
This skull of the Mosasaurus measures four and a half feet long and two and a half feet wide. The large pointed teeth on the jaws are very conspicuous; but, in addition to these, the gigantic reptile had teeth on a bone of the roof of the mouth (the pterygoid), like some of the modern lizards. The entire length of the animal has been estimated at about thirty feet. It is conjectured to have been able to swim well, and to have frequented the sea in quest of prey: its dentition shows its predatory and carnivorous character, and its remains have hitherto been met with exclusively in the chalk formations. Besides the specimens from St. Peter’s Mount, Maestricht, of which the above-described skull is the most remarkable, fossil bones and teeth of the Mosasaurus have been found in the chalk of Kent, and in the green-sand—a member of the cretaceous series—in New Jersey, United States of America. No animal like the Mosasaurus is now known to exist.