MAMMALIA. 719 



that the mother is browsing. Having thus acquired additional 

 strength, it quits the pouch, and hops at first with a feeble and 

 vacillating gait ; but continues to return to the pouch for occa- 

 sional shelter and supplies of food, till it has attained the weight 

 of ten pounds. After this it will occasionally insert its head for 

 the purpose of sucking, notwithstanding another fetus may have 

 been deposited in the pouch ; for the latter, as we have seen, 

 attaches itself to a different nipple from the one which had pre- 

 viously been in use." 



Thus therefore are we conducted by the Ovo-vivipara, as the 

 MAIISUPIALIA are properly called, to the most perfect or pla- 

 cental type of the generative system. 



(848.) Commencing our account of the reproductive organs of 

 VIVIPAROUS MAMMALIA, by examining those of the male sex, 

 we have another striking example of the insufficiency of the no- 

 menclature employed by the anatomist who confines his studies 

 to the human body, when it becomes necessary to describe cor- 

 responding organs even in animals organized after the same type. 



True it is, that there is the same general arrangement of the 

 generative apparatus ; and it is convenient, as far as possible, to 

 apply the same names to structures that apparently represent each 

 other : but a very superficial examination of the facts will serve to 

 show that great differences exist between them ; and, accordingly, 

 we are not surprised to find the utmost perplexity and confusion in 

 the descriptions of these parts, arising from the indiscriminate 

 application of the terms employed in human anatomy to totally 

 dissimilar structures. 



It is not, however, our business here to criticise the labours of 

 authors upon this subject; we must content ourselves with select- 

 ing an example of one of the more complex forms under which 

 the male genitals present themselves, and leave the reader to 

 contrast the various organs with those met with in the human 

 subject. 



The annexed figure (Jig. 332, A) represents the generative 

 viscera of the male Hedgehog. The rectum (a) and the neck of 

 the bladder (h) remain in situ ; but the rest of the latter viscus has 

 been removed, and the first portion of the urethra (e) slit open, 

 in order to show the relations of the surrounding parts. 



The testes (&, b) present the same structure in all the class, and 

 consist essentially of an immense assemblage of extremely delicate 

 tubuli semi?iiferi, enclosed in a dense albugineous tunic from 



