The variation of animals and plants under domestication . by the appendages,described by M. Eudes-Deslongchamps as often characteriz-ing the Normandy pigs. These appendages are always at-tached to the same spot, to the corners of the jaw; they arecylindrical, about three inches in length, covered withbristles, and with a pencil of bristles rising out of a sinuson one side: they have a cartilaginous centre, with twosmall longitudinal muscles: they occur either symmetricallyon both sides of the face or on one side alone. Richardsonfigures them on the gaunt old Irish Greyhound pig; andNathusius s

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The variation of animals and plants under domestication . by the appendages, described by M. Eudes-Deslongchamps as often characteriz-ing the Normandy pigs. These appendages are always at-tached to the same spot, to the corners of the jaw; they arecylindrical, about three inches in length, covered withbristles, and with a pencil of bristles rising out of a sinuson one side: they have a cartilaginous centre, with twosmall longitudinal muscles: they occur either symmetricallyon both sides of the face or on one side alone. Richardsonfigures them on the gaunt old Irish Greyhound pig; andNathusius state that they occasionally appear in all the longeared races, but are not strictly inherited, for they occur or 2* Edinburgh New lhilos;oph.Journal. April. 18(58. S ^r •xso DeBlainvilles Osteographie, p. 128. for various authorities outhis subject. Chap. III. THEIR VARIATION. 77 fail in animals of the same litter. As no wild pigs areknown to have analogous appendages, we have at present noreason to suppose that their appearance is due to reversion;. Fig. 4.—Old Irish Pig, with jaw-appendages. (Copied fromH. D. Eiehardsou on Pigs.) and if this be so, we are forced to admit that a somewhatcomplex, though apparently useless, structure may be sud-denly developed without the aid of selection. It is a remarkable fact that the boars of all domesticatedbreeds have much shorter tusks than wild boars. Many factsshow that with many animals the state of the hair is muchaffected by exposure to, or protection from, climate; andas we see that the state of the hair and teeth are correlatedin Turkish dogs (other analogous facts Avill be hereaftergiven), may we not venture to surmise that the reductionof the tusks in the domestic boar is related to his coat ofbristles being diminished from living under shelter? On theother hand, as we shall immediately see, the tusks and bristlesreappear with feral boars, which are no longer protected fromthe weather. It is not surprising that the tusks sh