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THE AMERICAN NATURALIST [Vol. XLYII1 



is confined to the aural and nuchal patches only, for else- 

 where the animal is black. In this case, too, the black 

 condition is probably derived, for youngish animals are 

 uniformly grizzled, and sometimes, apparently, this is 

 the adult condition as well. 



Among domesticated ungulates the same primary 

 patches are to be distinguished in cases where partial 

 albinism renders their bounds apparent, with the excep- 

 tion that in horses, cows and deer I have seen no clear 

 indication of the median crown patch which in mammals 

 is probably obsolescent. 



In both horses and cows the patches show interesting 

 and peculiar modifications. A series of diagrams (Figs. 

 25 to 32) show these patches in " calico' ' horses, though 

 not so fully as could be wished. The first indications of 

 areal restriction of pigment in horses appear in the shape 

 of a white "star" or round spot in the center of the fore- 

 head. This is often accompanied by white at the base of 

 the hoofs, or sometimes the entire foot is white producing 

 the so-called "white stockings." But there is no neces- 

 sary correlation between these white areas, such as 

 Brewer (1882) tried to show. The white on the forehead 

 may vary from a few white hairs to a broad blaze cover- 

 ing the entire front of the head between the eyes to the 

 muzzle. Sometimes the restriction of pigment is such as 

 to produce in addition to the white star on the forehead, 

 a white spot over each eye, and sometimes these three 

 spots are joined by a narrow unpigmented area. This 

 indicates that pigment production is weak at a spot 

 directly over the eye in comparison with neighboring 

 parts, and this no doubt accounts for the fact that 

 in black-and-tan or other dogs these are the pale spots 

 over the eyes where black pigment is not produced. 

 A white spot over the eye is also characteristic of many 

 rodents. 



Next after the restriction of the ear patches and the 

 drawing away of pigment from the feet, the most common 



