34 



COMPARATIVE ANATOMY 



cattle, the lateral glands of the Shrew, and the dorsal glands of 

 Hyrax resemble sweat-glands ; while the preputial and Meibo- 

 mian glands, the inguinal glands of certain Rodents, and the facial 

 glands of Bats, are largely, at any rate, modified sebaceous glands. 1 

 Another important modification of the integumentary glands 

 is seen in the characteristic mammary ylands, to the possession of 



A B 



g.m 



d. 



FIG. 26. A, VENTRAL VIEW OF A BROODING FEMALE OF Echidna hystrix. B, 

 DISSECTION OF THK VENTRAL INTEGUMENT FROM THE DORSAL (INNER) 

 SIDE. (After W. Haacke.) 



cl, cloaca ; t, T, the two tufts of hair in the lateral folds of the marsupial pouch 

 (b.m.) from which the secretion flows. On either side of the pouch, which 

 is surrounded by strong muscles, a group of mammary glands (y.m.) opens. 



which the Class owes its name, and which secrete milk for the 

 nourishment of the young. Nothing is known of their phylogeny 

 in the ancestors of Mammals, but in all cases they correspond to 



1 Amongst many other modifications of these glands of both types may be 

 mentioned the anal glands (especially well developed, e.ij., in Manis and the 

 Skunk) ; the perineal or prescrotal glands of Viverra ; the caudal gland of 

 the Fox and Wolf ; the suborbital or ant-orbital glands situated in the cavity of 

 the lacrymal bone in Cervidse ; and the interdigital glands of many Ruminants. 

 The preputial glands of the Beaver and Musk-deer also deserve special mention. 



A peculiar tubular, femoral or spur-gland is present at the knee in Echidna 

 and dorsal to the hip-joint in Ornithorhynchus, near the vertebral column. It 

 opens by means of a long duct on to the tarsal spur, and, though present in the 

 embryo of both sexes, undergoes reduction in the female. 



g. m. 



