GENERIC SUBDIVISION OF MEPHITINii:. 191 



of this duct is upon a papilla, which is situated on the side ot 

 the anus, just within the verge. Contraction of the muscular 

 investment compresses the sac, and causes the fluid to spirt 

 from the anal pore j the action is precisely that of a syringe 

 with compressible bulb. The Skunk is as cleanly as any 

 other animal, and the peculiar action observed at the moment 

 of the discharge prevents the wetting of the fur. Forcible 

 erection of the tail is accompanied by a tension of the perinoeum, 

 and an eversion of the anus, most favorable to forcible, unim- 

 peded, and direct evacuation of the contents of the sac. The 

 operation is wholly under the voluntary control of the animal, 

 and seems to be chiefly resorted to in self-defence, although 

 there is reason to suppose that the evacuation must recur at 

 intervals simply to avoid over-distension of a continually secret- 

 ing organ with its own products. Ordinarily, however, the 

 Skunk is not more odorous than many other animals ; it may 

 even be captured, under some circumstances, without provok- 

 ing an emission ; nor do the horrible possibilities of the stench 

 always render the flesh of the animal uneatable. In contem- 

 I)lating this singular provision of nature for the protection of 

 an otherwise inoffensive and almost defenceless creature, we 

 cannot but admire the simplicity of the means employed. Some 

 little further development of glands common to the MusteUdcv^ 

 and some inscrutable modification of the operations of the 

 secretory follicles, which gives a peculiar character to the fluid 

 elaborated, result in means of self-preservation as singular as 

 it is efficacious, habitual reliance upon which changes the 

 economy of the animal and impresses its whole nature. 



Division of the suhfamily into genera. 



There are two strongly marked generic types of the Mepliitina^ 

 one of them susceptible of subdivision into two subgenera. In 

 a former paper,* in which the skulls and teeth of the MepMtincv 

 were described, I allowed three full genera, following Dr. Gill ;t 

 but I am now rather inclined to consider SpiJogale as only a 

 subgenus. It certainly differs much less from Mephitis proper 

 than Conepatus does, and the degree of differentiation seems to 

 me to accord closely with that subsisting, for example, among 

 the subdivisions of the genus Futoriiis. 



* Bull. U. S. Geol. & Geogr. Siirv. Terr, ^d ser. no. 1, 1875, p. 1-2. 

 t Arranoj. Fara. Mamm. 187*2, 66. 



