202 HISTORICAL PALEONTOLOGY. 



Thuringia, but other allied species have been detected in the 

 Middle Permian of Germany and the north of England. This 

 Reptile attained a length of from three to four feet ; and it has 

 been generally referred to the group of the Lizards (Lacertilia}, 

 to which it is most nearly allied in its general structure, at the 

 same time that it differs from all existing members of this group 

 in the fact that its numerous conical and pointed teeth were 

 implanted in distinct sockets in the jaws this being a Croco- 

 dilian character. In other respects, however, Protorosaurus 

 approximates closely to the living Monitors ( Vara?iid<z) and 

 the fact that the bodies of the vertebrae are slightly cupped or 

 hollowed out at the ends would lead to the belief that the 

 animal was aquatic in its habits. At the same time, the 

 structure of the hind-limbs and their bony supports proves 

 clearly that it must have also possessed the power of progres- 

 sion upon the land. Various other Reptilian bones have been 

 described from the Permian formation, of which some are pro- 

 bably really referable to Labyrinthodonts, whilst others are 

 regarded by Professor Owen as referable to the order of the 

 " Theriodonts," in which the teeth are implanted in sockets, 

 and resemble those of carnivorous quadrupeds in consisting 

 of three groups in each jaw (namely, incisors, canines, and 

 molars). Lastly, in red sandstones of Permian age in Dum- 

 friesshire have been discovered the tracks of what would ap- 

 pear to have been Chelonians (Tortoises and Turtles); but it 

 would not be safe to accept this conclusion as certain upon the 

 evidence of footprints alone. The Chelichnus Duncani, how- 

 ever, described by Sir William Jardine in his magnificent work 

 on the ' Ichnology of Annandale/ bears a great resemblance 

 to the track of a Turtle. 



No remains of Birds or Quadrupeds have hitherto been 

 detected in deposits of Permian age. 



LITERATURE. 



The following works may be consulted by the student with regard to the 

 Permian formation and its fossils : 



(1) "On the Geological Relations and Internal Structure of the Magne- 



sian Limestone and the Lower Portions of the New Red Sand- 

 stone Series, &c." 'Trans. Geol. Soc.,' ser. 2, vol. iii. Sedg- 

 wick. 



(2) 'The Geology of Russia in Europe.' Murchison, De Verneuil, and 



Von Keyserling. 



(3) * Siluria. ' Murchison. 



(4) * Permische System in Sachsen.' Geinitz and Gutbier. 



(5) 'Die Versteinerungen des Deutschen Zechsteingebirges. ' Geinitz. 



(6) ' Die Animalischen Ueberreste der Dyas.' Geinitz. 



