IV. VEETEBRATA: MAMMALIA. 



617 



buzzards ; Cathartes aura* turkey buzzard. PANDIONID.E, Pandion 

 halmtus* fish hawk; FALCONID^E : Aquila* Halicetus,* eagles ; Buteo* 

 buzzards; Falco* falcons; Accipiter* hawks. Section II. STRIGES, 

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

 feathers; more closely related structurally to the Caprimulgidae than to 

 the Falconiformes. Bubo,* horned owls; Scops,* screech owls; Strix* 

 gray and brown owls ; Speotyto* burrowing owls. 



Class III. Mammalia. 



The mammals occupy the highest place among the vertebrates, 

 and consequently in the animal kingdom; they also possess a 

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

 belongs to the group, although separated in intelligence from the 

 most highly organized of the members by a wide gap. 



The most striking characteristics of the mammals again are 

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

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

 The hairs (fig. 645, H) are cuticular structures which are seated 



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

 oil gland; F, fat; (?, blood-vessels; GP, vascular papilla; If, hair; JV, nerves; J!VP, 

 nerve papilla; Sc, stratum corneum ; D, SD\ sweat gland and duct; M, 

 stratum Malpighii. 



on papillae of the derma, and are nourished by blood-vessels in 

 these. The lower end, the root of the hair, lies in a pit in the 

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

 the epithelial root sheath, 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. 



