138) of the “Kupfer-schiefer” of 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 Crocodilian character.  In other respects, however, Protorosaurus approximates closely to the living Monitors (Varanidoe); 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 progression upon the land.  Various other Reptilian bones have been described from the Permian formation, of which some are probably 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 Dumfriesshire have been discovered the tracks of what would appear 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, however, described by Sir William Jardine in his magnificent work on the ‘Ichnology of Annandale,’ bears a great resemblance to the track of a Turtle.

[Footnote 20:  Though commonly spelt as above, it is probable that the name of this Lizard was really intended to have been Proterosaurus—­from the Greek proteros, first; and saura, lizard:  and this spelling is followed by many writers.]

[Footnote 21:  In an extremely able paper upon the subject (Quart.  Journ.  Geol.  Soc., vol. xxvi.), Mr Etheridge has shown that there are good physical grounds for regarding the dolomitie conglomerate of Bristol as of Triassic age, and as probably corresponding in time with the Muschelkalk of the Continent.]

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
     Magnesian Limestone and the Lower Portions of the New Red
     Sandstone Series, &c.”—­’Trans.  Geol.  Soc.,’ ser. 2, vol. iii. 
     Sedgwick.
 (2) ‘The Geology of Russia in Europe.’