THE TRIASSIC PERIOD. 



225 



out at both ends, but the limbs appear to be adapted for pro- 

 gression on the land. The genus Belodon (fig. 152, c) is 

 known to occur in the Keuper of Germany and in America; 

 and Palaosaurus (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. 



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- 



Fig. 152. Triassic Reptiles, a. Skull of Nothosaurus mirabttis, reduced in size 

 Muschelkalk, Germany ; b, Tooth of Simomurus Gaillardoti, of the natural size 

 Muschelkalk, Germany ; c. Tooth of Belodon CarohnensisTrlas, America ; d, Tooth 

 of Thecodontotaurua antiquus, slightly enlarged Britain ; e, Tooth of Palceoauru 

 platyodon, of the natural size Britain. 



mensely elongated, and carrying numerous powerful conical 

 teeth implanted in distinct sockets. The teeth in Simosaurus 

 15 



