Structure of the Fossil Saurians. 287 



are, in some respects, totally different, and do not all possess 

 the Gavial-like beak and swimming organs of motion which 

 Geoffroy supposes in his family of Teleosaurians. Since this 

 arrangement cannot prove lasting, I assign the name of Te- 

 leosaurus only to the Gavial of Caen. My arrangement is 

 contained in the following table ; my chief object having been 

 to consider those Saurians more particularly which cannot 

 be arranged among the living genera. 



A. Saurians with Toes similar to those of the living Species. 



f 1 . Aeolodon H. v. M. ~\ 



12. Rhacheosaurus. 

 3. Pleurosaurus. I Fossil Saurians similar to 



I. With four toes. <J Geosaurus.* )► the living Caimans and 



Macrospondylus.* Gavial s. 



Mastodonsaurus.* 

 Lepidosaurus.* J 



TT Wfi fi J Protorosaurus H. v. M. "1 Fossil Saurians similar 



ii. with nve toes. | LacertaNeptunia Goldfuss.j to the living Lacerta?. 



B. Saurians with Limbs similar to those of the heavy Land Mammalia. 



1. Megalosaurus Buckland. 2. Iguanodon Mantell.f 



C. Saurians with Limbs for swimming. 



1. Ichthyosaurus Kb'nig. Saurodon Hays. 



2. Plesiosaurus Com/. Teleosaurus Geoffroy. 



3. Mososaurus Cony. Streptospondylus H. v. M. 

 Phytosaurus Jaeg. Metriorhynchus H. v. M. 

 Saurocephalus Harlan.^ 



D. Saurians with flying Limbs. 

 Pterodactylus Cuvier. 



A. Saurians with Toes similar to those of the living Species. 

 I. With Four Toes. 

 I. Aeo'lodon. 

 As one of the most complete, I place this Saurian before 

 the rest. Von Sbmmerring has described it fully under the 

 name of the Crocodilus priscus. The form of the head is, 

 in general, like that of the Gavial, while the structure itself 

 is however totally different, and the rest of the skeleton in- 

 dicates an animal which cannot be classed with the Croco- 

 diles. The beak of the fossil Saurus is somewhat shorter than 



* The extremities of these animals are either wholly or partially un- 

 known. The discovery of more perfect specimens will determine whether 

 this place in the series, thus temporarily assigned to them, be correct. 



f The Hyleosaurus of Dr. Mantell probably belongs to this division. 

 — Ed. 



% Referred to the fishes by Agassiz. — Ed. 



y 4 



