484 



MAMMALIA. 



glands (crumen) which are placed in a depression of the lacrymal 

 bone of antelopes and deer, the temporal glands of the elephant, 

 the facial glands of the bat, the pedal glands of ruminants, the 

 lateral glands of the shrew-mouse, the sacral glands of the 

 peccary, the caudal glands of the desman, the preputial glands 

 of the musk-deer and beaver, etc. These glands are often found 

 near the anus or in the inguinal region and then often open into 

 special cutaneous pits, e.g. the anal glands of many Carnivora, 

 Rodentia, and Edentata, the civet gland of the Viverridae, the 

 musk pouch of Moschus and the preputial glands of the male 



beaver. The lacrymal glands may 

 also be placed in the category of 

 cutaneous glands. 



The mammary glands occur in all 

 mammals. In monotremes they are 

 said to be modified sweat glands, but 

 in all other mammals there can be 

 little doubt that they are modified 

 sebaceous glands. In monotremes 

 they open on a shght depression of 

 the skin called the mammary areas 

 or pouches (Fig. 258). In many 

 mammals this area is much deepened 

 and the surrounding skin rises up 

 around it to form the teat, in 

 this case called a false teat, of 

 the gland (Ruminantia, Carnivora, etc.. Fig. 258). In others 

 there is no mammary pouch, but the area of skin on which the 

 glands open is simply raised into a papilla, the so called true 

 teat (primates, marsupials, Fig. 258). The position and number 

 of the mammary glands vary considerably. 



The skeleton consists of heavy bones, usually containing 

 marrow. 



The skull (Figs. 259, 260) differs from that of reptiles in the 

 following features. The primordial cartilage is completely 

 ossified and the separate bones, which are fewer than in rep- 

 tiles, meet and are separated only by sutures, which in old ani- 

 mals tend to disappear. In a few cases the bones become fused 

 in early hfe {Monotremata). There are no prefrontal or post- 

 frontal bones, and no membrane bone in the floor corresponding 



Fia. 258. — Diagrams showing the 

 different kinds of nipple met with 

 in mammals (from Gegenbaur). 

 A the monotreme condition. B 

 the true teat. C the false teat: 

 a periphery of glandular area ; 

 6 glandular area (mammary 

 pouch) ; gl glands. 



