FOSSIL FORMS. Fossil ancestors of the croco dilians are known from rocks as old as those of the Triassic, and they are found throughout the later rocks of Jurassic, Cretaceous, and Tertiary time. The more primitive forms, comprising the totally extinct sub-order Parasuchia, are repre sented by Belodon, from the tipper Keuper of Wiirttemberg and the Triassic sandstones of North _America ; Stagonolepis of the Triassic of Scot land, and Parasuchus from the Gondwana series of central India. These three have long, narrow snouts, produced by the elongation of the pre maxilla•y hones, and in the structure of their skulls they present some points of resemblance to the primitive dinosaurs and to the rhynehoce phalians. The Mesosuchia of Jurassic age, mostly reptiles of small size, have both long and short snouted forms, that differ from the Eusuchia in respect of the form of the palate. Eustachian tithes, and vertebrfe. The principal genera are Pelagosaurus, Metriorhynchus, Theriosuchus, Notosuchus, Teleosaurus, Stenosaurus, from the Jurassic of Europe. The Eusuchia, also with
both broad and long-snouted species, range front the Upper Jurassic through the Cretaceous and Tertiary, and comprise all the recent species, in which the Eustachian tubes are inclosed by bone and the vertebral centra are proccelous. Direct ancestors of the Malayan genus Tomistoma are found in the Miocene beds of the eastern Mediter ranean region of south Europe. During the Eocene, typical gavials lived in the seas of Eng land, but they migrated southward during subse quent Tertiary time, and their remains are found fossilized in the Pliocene deposits of the Siwalik Hills of India. The largest known crocodile was probably the genus Ehamphosuchns, from the Pliocene of the Siwalik Hills, India, with a length of over fifty feet.