Blucl--au(l-tan Pattern of Domestic Doga. 193 



liair clsewliere, and tlwit the black corresponds to the darker 

 portions of the body, wlicre tlie hair is richly pif^mented, in 

 the wild animals. This statement only needs qnalitication 

 with respect to the tan spots over the eyes, the hoinolo;^ues of 

 which are by no nu'.uis always visii)le in wild doo^s, or, at all 

 events, are notsnfKciently evident to carry absolute conviction 

 as to their presence. This is the case with examples of the 

 foUowinn^ species now livin;]^ in the Zoolo^^ical Gardens : — 

 Cdut's hitraus, nut/iiis, htpaster, aureiia, and mesomelas* ; Caon 

 duh'fiHfiensisnud alphius. On the other hand they are detect- 

 able, thou,i,di minute, in some cxamjdes of Vulpes vulpes^ and 

 visible, though not consj)icuous, in two Dingos which I have 

 reason to think have a monfjrel strain of domestic doof. In 

 the case, however, of the wolves now or lately living in the 

 Gardens, namely in a Siberian example of C. Inpna, in three 

 specimens of C. lupus occidentalism and in one of C. pallipeSy 

 there is no possibility of overlooking^ them. Altliou^rh not 

 emphasized by a settin<x of jet-black hair, they nevertheless 

 show up as pale spots relatively as lar^e as the corresponding 

 tan spots in do^s. Their conspicuousness in these species 

 su;2:irests, though it does not prove, a preponderance of the wolf 

 strain over that of jackals in our breeds of domestic dogs. 



Black-and-tan dogs may be termed melanescent, or, 

 preferably, nigrescent sports. Were they completely melan- 

 i.stic or perfect "melanos" they would be black all over, as 

 many dogs are. It is evident that the tan stands in the same 

 relation to the pale areas as the black does to the more 

 heavily pigmented areas of the wild species; and it is a 

 highly interesting fact that the nigrescent sport throws back 

 to the type of pattern characteristic of a parent form. Tan 

 is merely one of the shades of that class of colour which is 

 conmioidy called " erythristic^' ; and, assuming the truth of 

 the above-given explanation of the occurrence of tan in 

 dogs, it appears that albinism, erytlirism, and melanism are 

 three consecutive stages in colour-variation, erytlnisni being 

 the incipient stage eitlier of albinism or melanism, according 

 as the organism is albescent or nigrescent — that is to say, 

 assuming or tending to assume the albino or melano livery. 



I believe this "law" of colour-change will prove to be 

 ca|)able of wide application in the Mammalia and probably 

 outside the linnts of that class. For examj)li>, there are in 

 the Zoological Gardens at the present time some black-and-tan 

 niouHon [Ovis musimon). In these animals the white jiortioiis 

 of the typical wild sheep are tan and the rest of the coat 



♦ This is not Btrictly true of all examples of this .«pecie9. 

 Ann. iL Mag. N. Hist. Ser. 7. Vol. xix. 13 



