572 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [June 8. 
do in the old ones, the hind limb being considerably longer in the 
former, in proportion to the fore limb, than is the case in P. Speneri. 
The difference likewise is strongly marked in the proportions of the 
humerus. On referring to von Meyer’s tab. ix., above quoted, the 
constricted part of the shaft of the humerus therein figured measures 
2 inch wide, while the distal extremity is # inch across: thus it 
appears that the latter part is three times wider than the former. 
In P. Husleyi the narrow part of the humerus is + inch thick, and 
the distal extremity is 2 inch wide: so here the disparity is only 
as two to one, but in P. Speneri it is as three to one. It must be 
stated, too, that in the old species the proximal end of the humerus 
is nearly as wide as the distal, while in the new species it is only 
slightly enlarged. 
EXPLANATION OF PLATES XXXIX. & XL. 
Puate XXXIX. 
Slab of Marl-slate from Midderidge, containing the vertebral column &e. of 
Proterosaurus Spenert, von Meyer. 
PuatTe XL. 
Slab of Marl-slate from Midderidge, containing the skeleton of Proterosaurus 
Huxleyi, sp. nov., Hancock and Howse. 
