Xii.] THE EXCRETORY ORGANS. 487 



flank, as in the Shrews ; or there may be a glandular sac 

 opening near the armpit, as in the Bat Cheirojiielcs. 



There may be a gland in the sacral region of the back, 

 opening by a median orifice like a dorsal navel, as in the 

 Peccari. 



There may be a gland in each groin, as in the Corinne 

 Antelope, or placed more medianly and post-axially, as in 

 the Musk Deer, where the sac may be three inches broad. 



Scent-glands may open at or near the post-axial termina- 

 tion of the intestine, as in many Carnivora, e.g. the Skunk 

 and Hyaena. In the higher division of man's order (the 

 Apes) there are no such glandular structures, but in the 

 Lemuroids (e.g. Cheirotnys] there may be a shallow pit-like 

 gland on each side of the end of the alimentary tube. 



There may be a scent-gland in the tail, as in the Desman 

 and the Fox, or near the arm, as in certain Bats (Einballonura 

 and Saccopteryx), where there is a glandular sac in each 

 wing-membrane. 



A glandular structure may open behind the foot, as in the 

 Rhinoceros, or in front of it, between the toes, as in the 

 Sheep. 



We may find (as in the male Ornithorhynchus and 

 Echidna) a large gland placed in the leg, and furnished 

 with a long duct which passes to the heel and there traverses 

 a perforated spur like the poison-fang of a Serpent, though it 

 does not seem to poison, or even to be used for defence. 



In descending below man's class to Birds, we find a 

 peculiar cutaneous structure, the " uropygial gland" consist- 

 ing of two parts conjoined, and in the Swan measuring an 

 inch and a half in length. It is placed upon the more post- 

 axial caudal vertebras and ploughshare bone, and opens on 

 the skin, where it discharges a greasy fluid to lubricate the 

 feathers. 



Another glandular structure is present in Birds, the Bursa 

 Fabricii. This is a conical cavity which opens into the post- 

 axial region of the cloaca. It is placed between the ureters, 

 on the ventral aspect of the sacrum. 



In Reptiles we may find other structures. Thus there may 

 be, as in the Crocodile, a musky gland inside the mandible ; 

 or beneath it, as in the Indian Tortoise. There may be a 

 glandular fossa opening into the dorsal aspect of the cloaca, 

 as in the Terrapins ; or a pair of elongated sacs opening 

 beside the post-axial termination of the intestine, as in the 

 common Snake ; or a pair of glandular depressions of the 



