58 MAMMALIA. 



dentia there are animals, as the Rat, in which there are as many as 

 three pairs of prostate glands. 



Cowper's glands likewise exhibit remarkable complexities ; and 

 perhaps in no part of the anatomy of the Mammalia does greater 

 variety prevail. As a rule, allied genera have them formed alike, 

 while in one and the same order great diversities occur. In the 

 Apes these glands are mostly larger than in Man ; in the Cheirop- 

 tera and Carnivora they are often very conspicuous, as in Sorex, 

 Hyaena, Viverra, arid also in the herbivorous Marsupiata ; they are, 

 on the contrary, very small in the Dog, Cat, and Fox. They are 

 very much developed in many Rodentia, as Myoxus and Castor, and 

 in the Hog, Elephant, and Camel. In Dipus they form a pair of dis- 

 tinct sacs, and in the Hedge-hog they are long, and contorted. In 

 the Hedge-hog, the Mole, and Insectivora generally, they are most 

 conspicuous, and form at times large flat lobed glands, composed of 

 tufts of delicate ccecal tubes. 



The Penis of the male also exhibits exceedingly great diversities 

 It is only in the Apes and Cheiroptera that it hangs down freely, 

 as in Man, from the pubic arch. In the Cats and many Rodentia 

 it is directed backward. In the Marsupiata the opening of the 

 prepuce is even surrounded by the sphincter ani muscle, and in the 

 Beaver it is so drawn back that the entrance into it nearly resem- 

 bles a vagina. These relations are occasioned by the prepuce or bag 

 of the penis commonly investing the organ in such a way, that in 

 its usual position the penis is retracted within it as in a sheath. 

 This vagina-shaped prepuce opens for the most part behind the um- 

 bilicus, and when the penis is long, it lies within the sheath with 

 either a simple or double S-shaped curve ; this is the case to a very 

 great degree in the Elephant. In the Hog there lies internally, upon 

 each side of the prepuce, a small folded ccecal pouch, which is apt to 

 retain some of the urine as it escapes, and in which calculi easily 

 form. Animals having the penis directed backward micturate also 

 in that direction, but during copulation, when it is erected, the pe- 

 nis stands forward. The suspensory ligament arising from the pubic 

 arch is in man and most Mammalia feebly developed ; but in large 

 animals, as the Pachydermata and Solipedia, it is very strong and 

 remarkable, in order to support the great weight of the penis. In the 

 orders just mentioned, as also in most Ruminantia and Carnivora, 

 the prepuce is drawn back from over the penis by a pair of retractor 

 muscles, which arise from the abdomino-tegumentary muscles ; while 

 by another pair of retractors arising from the first caudal vertebrae 



