160 EVOLUTION AND DISEASE. 
truly atavistic, and the leading features in the argument 
are visually represented in the drawings (fig. 84). 
The museum of the Ecole Vétérinaire de Lyons con- 
tains a very remarkable specimen. It is the skeleton of 
an equine manus with two functional digits (fig. 85), 
on each side of the metacarpal bone a vestigial 
metacarpal exists as in the normal manus. In the 
specimen last considered we noted that the super- 
numerary digit was articulated with the distal end of 
the lateral metacarpal (fig. 85, B). In the Lyons speci- 
Fic. 84.—A, the manus of Azppfarion ; B, the 
manus of a horse( £ywzs) with the inner digit 
functional (atavistic) ; C, the normal manus 
of Aguus, one toe functional, ii. and iv. 
vestigial. 
men both digits articulate with the main metacarpal ; 
and it is clear from even a cursory examination of the 
preparation that we have to deal with an example of 
dichotomy, or bifurcation of the terminal segments of 
the functional digit. 
The museum of the Royal College of Surgeons, 
England, contains a skeleton of an equine manus with a 
supernumerary digit of this character, but it differs from 
the Lyons specimen in that the third digit has dich- 
