Fossils. 
143 
at right angles to the line of the middle toe, but yet 
are not identical with those of any known batrachian 
or reptile. Still it has been conjectured by .the same 
great authority, as well as by others, that these foot- 
prints were the work of the creatures now known as 
Labyrinthodonts, which have left their remains in 
rocks of the Carboniferous, the Triassic, and the Per- 
mian ages. He argued as follows : — 
(1) There is proof from the skeleton that the 
Labyrinthodon had hind limbs larger than its fore 
limbs. 
Fig. 35. — Skull of Mastodonsaurus. 
(2) That the size of the known species of Labyrin- 
thodon corresponds with the size of the footprints of 
the Cheirotherium. 
(3) The Labyrinthodon occurs in the Triassic 
strata, in which the Cheirotherium impressions are 
found. 
