62 



VARIATION 



6. Foal with right fore foot bearing two complete digits symmetrically 

 developed, each bearing well-formed hoofs that are flattened on the inner 

 sides and curve toward each other like those of the artiodactyles (cattle, 

 etc.). This illustrates condition (3) 

 just mentioned (see Fig. 13). 



Cattle, sheep, and pigs af- 

 ford deviations no less inter- 

 esting : 1 



FIG. 13. Foot of horse : digit ill sup- 

 pressed, digits ii and iv developed. 

 After Bateson 



i. Calf having three digits on 

 right fore foot, borne on a single 



common bone after the fashion of the birds and fully 

 symmetrical (see Fig. 14). 



2. Heifer having three fully developed toes on 

 each hind limb. In this case the supernumerary was 

 clearly digit n. 



3. Calf with "supernumerary toe placed between 

 the digits of the right manus (fore foot). This toe 



had a hoof and seemed ex- 

 ternally to be perfect, but on 

 dissection it was found to 

 contain no ossification, but 

 was entirely composed of 

 fibrous tissue and fat." 2 



4. Cow, full-grown, right 

 fore foot with four digits 

 arranged in two groups of 

 two each (see Fig. 15). 



This is clearly a case in 

 which the increase is due, 

 not to the reappearance of 

 an ancient lost toe like n or 

 v, but rather to the doubling 

 of the normal digits ill and 

 iv through ordinary meristic 

 variation? 



5. Calf, left hind foot 

 with five toes, "an inner 



three digits group of two toes curving 

 toward each other, and an 

 outer group of three, of 



FIG. 14. Right fore foot of calf: 



present, each supplied with both flexor and 

 extensor tendons. After Bateson 



p. 377. 



1 Bateson, Materials, etc., pp. 373-390. 2 



8 No case is better than this to suggest caution to the student of evolution. 

 When an extra toe appears among those forms whose ancestors were known to 



