286 Structure of the Fossil Saurians. 



found the Mammalia which possess limbs adapted for swim- 

 ming (the Fish-like Mammalia), and the Bats, in a fossil state; 

 since we now know it by no other means than that the class 

 of Mammalia is formed according to these types. We ought, 

 in fact, rather to wonder that there are bird-like flying and 

 fish-like swimming Mammalia, than that there are such 

 Saurians, since these last naturally stand in a closer relation 

 to birds and fishes than the Mammalia. It now becomes a 

 question, whether there were not merely Vivipara,* but even 

 Mammalia, among the Saurians? 



The tertiary deposits chiefly contain Saurians which are 

 analogous to our present crocodiles and lizards. The chalk 

 and the green sand also afford examples which are similar to 

 the recent Saurians. The structure of the Saurians of the 

 transition strata is, on the contrary, for the most part very 

 dissimilar. I have already communicated these results, to- 

 gether with the essential parts of my system, in September, 

 1829, at the meeting of Naturalists and Physicians, at Hei- 

 delberg. More recently, at the sitting of the Academy at 

 Paris, on the 9th of May, 1831, Geoffroy declared, that 

 Crocodiles were found only in the tertiary formations, and 

 that it is only the large Saurians of the gypsum beds of 

 Montmartre, of the pottery clay of Auteuil., and of the chalk (?) 

 of Meudon, which are true Crocodiles, and similar in their 

 forms to the Caimans or Crocodiles, with short beaks. On 

 the other hand, those with pointed beaks, with jaws like 

 those of the Gavials, are, he stated, from the marine beds of 

 the transition order, and are of an older family, and of a dif- 

 ferent type. At first, this difference struck Geoffroy only as 

 regards the Gavial of Caen, which he, for this reason, named 

 the Teleosaurus. He now bestows the same name on the 

 whole tribe of Saurians with beaks similar to those of Gavials 

 of the regular type, and distinguishes among them several 

 species ; among which, for instance, are the Gavials of Som- 

 merring and Faujas, those of Havre and of Honfleur, the 

 Crocodile of the collection of Geneva, the crocodile of Boll, 

 and, finally, all the Saurians of the Oolite of Normandy. 

 These creatures, however, which Geoffroy here seeks to unite, 



* Vivipara occur in most divisions of animals. Among the cold-blooded 

 Vivipara there are, the so termed false or apparent Vivipara. Rennie 

 and James Starck have remarked, that the Lacerta dgitis, which in Germany 

 and France lays eggs, in Scotland brings forth its young alive. Oviparous 

 snakes may be made to produce their young alive by hindering them from 

 casting their skin, and retarding them in their time of laying. Besides this, 

 the poisonous snakes, as far as we know them, are viviparous. Among the 

 Batrachians, as well as among the fish, are several kinds which bring their 

 young alive into the world. 



