26 ELEMENTS OF MAMMALIAN ANATOMY 



At the orifices of the internal passages, such as the diges- 

 tive and genital tracts, the epithelium changes to a soft deli- 

 cate nature, and is then known throughout these passages as 

 mucous membrane. 



The coriiim or dermis is a form of fibrous connective tissue 

 whose deepest portion forms the white fluffy areolar sub- 

 stance cut in remo\ing the skin. In many regions just below 

 the true skin is a layer of adipose tissue, which when examined 

 under the microscope is seen to be composed of numerous 

 globular fat-cells supported by fibrous areolar tissue. The 

 seven pads on the forepaw and the five on the hind one con- 

 sist of greatly thickened epidermis, the corium, and masses 

 of fibrous connective tissue enveloping many fat-cells. 



The sebaceous or oil glands lie in the corium, and by means 

 of a duct open into the hair follicle near the surface. The 

 sudoriferous or sweat glands, composed of coiled tubes, are 

 present in the subcutaneous tissue, from whence a duct ex- 

 tends to the surface. Although there are no blood-vessels 

 in the epidermis, numerous nerve terminations are present 

 in the deeper portions. The true skin is richly supplied with 

 both nerves and blood-vessels. 



The claws produced by a special modification of the epider- 

 mis are among the most important appendages of the skin. 

 Five of these are present on each forefoot, while only four 

 occur on the hind one. At the root of each claw, the dermis 

 forms a crescentic fold over it, and beneath is a number of 

 papilla? richly suppHed with blood-vessels. This entire struc- 

 ture forms the matrix of the claw, which is set around the 

 terminal part of the distal phalanx of each digit. Claws, or 

 sonle similar structures, such as nails or hoofs, are present in 

 all mammals except the Cetacea. 



Another important appendage of the skin is the hair, which 

 covers the entire body except the tip of the nose and the pads 

 of the feet. Its length and color vary with the variety of the 

 cat. The Mombus cat of Africa has short stiff hair, while 



