39« ; 



THE AMEBIC AX XATURALIST [Vol. XL VIII 



very rare to see the two rump centers separated, but 

 instead, as in Figs. 10 and 14, they appear, when much 

 reduced, as a small median spot at the root of the 

 tail. That they were originally paired, there is no doubt, 

 as there is frequently (as in Fig. 9) a deep median 

 notch indicating the median primary break between the 

 centers, or (as in 'Figs. 11, 12) one of the lateral centers 

 drops out, leaving its fellow of the opposite side. The 

 continued union of the side patches with the shoulder 

 patches is seen in Fig. 7, while in Fig. 9, though the union 

 is -till present between these patches of the right side, on 

 the left side the shoulder patch has failed to develop, and 

 the side patch is so reduced that it does not meet its 

 fellow of the right. In Fig. 8 both shoulder patches are 

 present more or less bilaterally equal, and, as frequently, 

 are produced into narrow tongues on to the upper arm. 

 The two side patches in Fig. 8 are also reduced, so as to 

 be wholly separated from each other and from the neigh- 

 boring centers. They are further interesting in being 

 placed nearly median one behind the other instead of 

 nearly opposite. In Fig. 11, on the other hand, they are 

 far sundered, but this, in dogs, is a much less usual con- 

 dition. In Fig. 10 a single median dorsal patch repre- 

 sents the slightly developed side patches, but whether 

 this single patch corresponds to one or other of the two 

 centers, or whether the two are actually fused in the 

 dorsal line, I can not yet say. 



The shoulder centers, when slightly reduced, are large 

 in dogs, and cover a considerable saddle-shaped area, as 

 indicated in Fig. 5, from near the center of the back for- 

 ward including the fore leg and part of the fore shoulder. 

 When further reduction takes place the pigment is drawn 

 away from the extremities and the saddle separates from 

 the neck patch (Figs. 2, 6) and then from the side patch 

 (Figs. 5, 9), and finally the shoulder patches separate 

 from each other (Fig. 8). One or other of the shoulder 

 patches may drop out entirely (Fig. 10) or be reduced to 

 a very small spot (Fig. 12) at what may be considered 



