THE TRIASSIC PERIOD. 



2I 9 



and Palceosaurus (fig. 153, e) has also been found in the Trias 

 of the same region. Teeth of the latter, however, are found, 

 along with remains of Thecodontosaurus (fig. 153, d\ in a 

 singular magnesian conglomerate near Bristol, which was 

 originally believed to be of Permian age, but which appears 

 to be undoubtedly Triassic. 



Fig. 152. Triassic Reptiles, a, Skull of Nothosaunts miralnlis, reduced in size Mus- 

 chelkalk, Germany ; b, Tooth of Simosaurns Gaillnrdoti, of the natural size Muschel- 

 kalk, Germany ; c, Tooth of Belodon Carotinerisis'l'rias, America ; d, Tooth of Theco- 

 dontosanriis antiquus, slightly enlarged Britain; e, Tooth of Palaosaurus platyodon, of 

 the natural size Britain. 



The Trias has also yielded the remains of the great marine 

 reptiles which are often spoken of collectively as the " Enalio- 

 saurians" or " Sea-lizards," and which will be more particularly 

 spoken of in treating of the Jurassic period, of which they are 

 more especially characteristic. In all these reptiles the limbs 

 are flattened out, the digits being enclosed in a continuous 

 skin, thus forming powerful swimming-paddles, resembling the 

 "flippers" of the Whales and Dolphins both in their general 

 structure and in function. The tail is also long, and adapted 

 to act as a swimming-organ ; and there can be no doubt but 

 that these extraordinary and often colossal reptiles frequented 

 the sea, and only occasionally came to the land. The Triassic 

 Enaliosaurs belong to a group of which the later genus 

 Plesiosaurus is the type (the Sauropterygia). One of the best 

 known of the Triassic genera is Nothosaurus (fig. 152, a), in 

 which the neck was long and bird-like, the jaws being im- 

 mensely elongated, and carrying numerous powerful conical 

 teeth implanted in distinct sockets. The teeth in Stmosaunts 

 (152, b] are of a similar nature ; but the orbits are of enormous 

 size, indicating eyes of corresponding dimensions, and perhaps 

 pointing to the nocturnal'habits of the animal. In the singular 



