490 ELEMENTARY ANATOMY. [LESS. 



of inguinal and also a pair of pectoral ones, as in Tarsius ; 

 or two pairs of pectoral mammary glands, as in Galago. 



Each teat is traversed by a single efferent canal in Rumi- 

 nants, Pigs, and Cetaceans ; by two in Horses and Apes ; 

 by five or six in some Rodents and Carnivora ; and by more 

 in the Elephant, Sirenia, Marsupials, and higher Primates. 



As has been said, mammary glands are confined to man's 

 class : the only faint adumbration of such organs, outside his 

 class, is to be found in Pigeons, where the crop secretes a 

 milky fluid (during the breeding season) which mixes with 

 the food taken into that receptacle the mixture serving as 

 food for the young. It has also been asserted that glands 

 lining the pouch of the Fish Hippocampus secrete a nutritious 

 fluid useful to its progeny. 



1 6. Having now completed our elementary investigation 

 and exposition of the various organs and parts which make 

 up man's body, and having noted the more important dif- 

 ferences which the corresponding structures may present in 

 other Vertebrate animals, it may be well shortly to re- 

 capitulate some of the leading distinctions in a different 

 sequence and arrangement, in order to bring out more 

 clearly not only the peculiarities, but also the affinities 

 evidenced by various anatomical relations between the body 

 of man and those of other Vertebrates. 



In the first place MAN differs from the entire class of 

 FISHES in the following points : 



(1) He has a skeleton the appendicular parts of which 



are divided into upper-arm, fore-arm and hand, and 

 thigh, leg, and foot, respectively. 



(2) His hyoid is a small structure with one pair of cornua 



instead of several branchial arches. 



(3) His skull is formed with a large basi-sphenoid but no 



para-sphenoid ; with a large squamosal confluent 

 with a " petrous bone ;" and with a mandible 

 formed of two united pieces directly suspended 

 from the squamosal. 



(4) His auditory ossicles are minute, and take no part in 



suspending the mandible. 



(5) His ribs, articulated dorsally by head and tubercle, are 



connected on the ventral side with a sternum. 



(6) His vertebrae have at first terminal epiphyses. 



(7) He has a pelvis formed of two ilia, two ischia, and two 



pubes united dorsally to a sacrum. 



