362 Dr Adam on the Oateolo^y of the Hippopotamus. 



Five dimensions still more characteristic are twice the dimen- 

 sions above stated : 



1. In the vertebral column ; the transverse breadth of the atlas, equalled 

 by that of no other dorsal or cervical vertebra, 



2. and 3. The breadth of the cranium, at the orbits, and at the sockets of 

 the tusks. 



4. The greatest expansion of the scapula. 

 6. The length of the first rib. 



The foregoing dimensions being as one and two, the follow- 

 ing are as three : 



]. and 2. The transverse breadth of the second and fourth of four lumbar 

 vertebrae (the third and broadest is I -12th broader than these two). 



3. The inial breadth of the lower jaw being the greatest breadth of the 

 head. 



4. The length of the palate. 



5. The length of the scapula from the glenoid cavity. 



6. The greatest length of the humerus. 



7. The length of the femur from the cervix to the rotular groove. 



Connected probably with the uncouth figure of the hippopo- 

 tamus, is the imperfect symmetry of the pelvis in relation to the 

 cranium. 



The acetabular breadth is the same as the zygomatic breadth ; 

 a dimension of the cranium of this animal subordinate to that of 

 the lower jaw. Besides ; intermediately to the acetabula and the 

 ischial tuberosities, the pelvic breadth is half the inial breadth of 

 the lower jaw. 



The three classes of identical dimensions to which this notice 

 has been limited, are according to a very fine osteological speci- 

 men of a male hippopotamus in the Museum of the Royal Col- 

 lege of Surgeons of London. The actual dimensions are, 5,55, 

 11.10, 15.65 inches. 



Though, owing to the multiplicity of osteological, as of other 

 living forms, it seems hardly possible to assign any one osteolo- 

 gical dimension as a standard of reference for the dimensions 

 even of mammalians alone, it follows from what has been above 

 stated, that the general comparison and precise arrangement of 

 animals may perhaps be attained by viewing their osteological 

 dimensions in combination. We may suppose a range of equi- 

 distant planes parallel to the mesial plane, by which planes the 

 constant dimensions of breadth may be considered as bounded ; 



