IV. VERTEBRATA: MAMMALIA. 



617 



buzzards ; Cathartes aura,'- turkey buzzard. Pandionid^, Pandion 

 halicetm* fish hawk; Falcunid.e : Aquila* HaUatus* eagles ; Buteo* 

 buzzards; Falm* falcons; AcciiMer* hawks. Section II, STRIGES, 

 owls; compact birds with loose, fluffy plumage, large eyes in a circle of 

 feathers; more closely related structurally to the Caprimulgidte than to 

 the Falcouiformes. Bubo,'* horned owls; Scops,'-* screech owls; Strix;* 

 gray and brown owls ; Hprntyto,'* burrowing owls. 



Class III. Mammalia. 



The mammals occuj:)}' the highest place among the vertebrates, 

 and consequently in the animal kingdom; they also possess a 

 special interest for ns, for man, in structure and development, 

 belongs to the groirp, although separated in intelligence from tlie 

 most highly organized of the members by a wide gap. 



The most striking cliaracteristics of the mammals are again 

 furnished by the skin. In fact one may, ^vith Oken, call them 

 hair-animals, since hair is as diagnostic as leathers are for birds. 

 The hairs (fig. G-IS, //) are cuticular structures which are seated 



Fw. 645,— Section of skin of man, (From "Wiedersheim.) Co, derma (corium); D, 

 oil gland; ¥, fat: (i, blood-vessels; (H\ vascular papilla: U. hair; N, nerves; NP, 

 nerve papilla ; ,Sc, stratum corneum ; ND, SD', sweat gland and duct ; S,.V, 

 stratum Malpigbii, 



on papillaB of the derma, and are nonrislied by blood-vessels in 

 these. Tlie lower end, the root of the hair, lies in a joit in the 

 epidermis, the hair follicle, and is surrottnded by a double envelope, 

 the epithelial root sheatli, formed by an inpushing of the epidermis 

 and an outer connective-tissue follicular sheath. Small muscles 

 attached to the base of the larger hairs serve for their erection. 



