No. 571] PAT TEEN DEVELOPMENT 



the ultimate center of the pigment patch, near the upper 

 part of the body, near or just back of the shoulder. The 

 ear patches seem to be the last to disappear, and these, 

 too, may be variously reduced or only one may be present 

 (Fig. 15). The approximate outlines of the patches when 

 fully developed are indicated by dotted lines in Fig. 15, 

 in which 1 is the crown patch, 2 the ear patch, 3 the neck 

 patch, 4 the shoulder patch, 5 the side patch, and 6 the 

 rump patch. 



In dogs, there is seldom seen any tendency for these 

 primary patches to divide. What has the appearance of 

 such a tendency is seen, for example, in the coach dog, 

 which is rather evenly flecked with rounded black spots, 

 with often in addition, black ears and more rarely reduced 

 rum]) patches. Fig. 9 shows such a dog in which both ear 

 patches, one shoulder, both side and both rump patches 

 are sharply indicated, though reduced. In addition there 

 are present on the white body areas between, many small 

 flecks of dark color, evenly distributed, which are clearly 

 not islands separated from the primary patches. Indeed 

 this spotting seems to constitute a wholly different cate- 

 gory of pigment formation, in addition to that of the 

 primary patches, which latter I have called "centripetal" 

 pigmentation. As Professor Castle suggests to me, it is 

 probably homologous with the "English" marking or 

 spotted condition of domesticated rabbits, and possibly 

 the dappling of horses is a similar phenomenon. When 

 these spots and the primary color patches are of the same 

 hue, it is not possible to distinguish the two in visual 

 appearance, unless the latter are reduced areally, when, 

 as is sometimes the case in the coach dog, one or more of 

 the primary patches is seen with the spots, as it were, 

 proliferating from its edge. This second element no 

 doubt enters as a factor in the color pattern when the 

 small spots are of a different color from that of the 

 general body surface, as in case of the cheetah (Cynce- 

 lurus) or the leopard and jaguar. 



I am inclined to think that the excessive breaking up of 



