MAMMALIA. 



no pelvis is met \vith, the ossa ischii exist, apparently only for the 

 purpose of giving firm support to the origin of the parts in ques- 

 tion. The size of the corpora cavernosa in Man, and many other 

 animals, is of itself sufficient to give the needful rigidity to the parts 

 during sexual excitement ; but in some tribes an additional provision 

 is required to ensure adequate firmness. Thus in Monkeys, Bats., 

 the CARNIVORA, the RODENTIA, and the Baltenidte among CETA- 

 CEANS, a bone is embedded in the substance of the male organ, of 

 which it forms a considerable part. Where this bone exists, the 

 corpora cavernosa are proportionately small, and the fibrous walls 

 of the penis are confounded with its periosteal covering. 



The corpus spongiosum, likewise composed of erectile tissue, is 

 quite distinct from the cavernous bodies, and, as we have said 

 before, is only found in the Mammifera. It commences by a bulb- 

 ous origin that embraces the urethra, and it accompanies that 

 canal quite to the extremity of the penis, where it dilates into the 

 glans. 



The size and shape of the male organ varies of course in every 

 genus of quadrupeds, as does the form and texture of the glans. 

 To describe these would lead us into details of too little import- 

 ance to be noticed in a survey so general as that we are now 

 taking ; nevertheless, we cannot entirely omit to notice the strange 

 and unaccountable structure met with in some of the Rodent tribes, 

 whereby the penis is rendered a most formidable-looking apparatus, 

 the object of which it is not easy to conjecture ; although as an 

 instrument of excitement no one will be disposed to deny its 

 efficiency. 



Thus, in the Guinea-pig tribe (Cavia, Ilig.) the penis is 

 strengthened by a flat bone that reaches forward as far as the 

 extremity of the gland beneath which is the termination of the 

 urethra ; but behind and below the orifice of this canal is the 

 opening of a pouch, wherein are lodged two long horny spikes. 

 When the member is erect, the pouch alluded to becomes everted, 

 and the spikes (Jig. 333, d) are protruded externally to a consi- 

 derable length. Both the evected pouch (b) and the entire sur- 

 face of the glans are, moreover, covered densely with sharp spines 

 or hooklets ; and, as though even all this were not sufficient to 

 produce the needful irritation, still further back there are, in some 

 species, two sharp and strong horny saws (c, c) appended to the 

 sides of the organ. From this terrible armature of the male 



