102 EVERs's COMPARATIVE ANATOMY. 



is more constant in its existence than the vesiculae, being found in 

 all orders of the mammalia, excepting perhaps the greater number 

 of the rodentia and insectivora. It is double in the elephant, the 

 camel, the horse, and some others. Compels glands, which are 

 small, and situate behind the bulb of the urethra in the human 

 subject, are large, and often increased in number in other animals, 

 thus in the opossum and kangaroo-rat there are four, and in the 

 wombat, kangaroo, and others, as many as six. They are absent 

 from the greater number of carnivora, ruminantia, and cetacea. In 

 the marsupiata they are covered by a strong muscular stratum, and 

 in the icheneumon, their ducts run forward, and open near the 

 extremity of the penis. 



Penis. — This organ is modified considerably throughout the 

 class. Thus, in the digitigrade carnivora, as the dog and the lion, its 

 two crura are separated by a distinct fibrous septum, which is absent 

 in the cetacea, pachydermata, and plantigrade carnivora. In the 

 cheiroptera, qnadrumana, cetacea, rodentia, and carnivora, with the 

 exception of the hyena, and a few others, the penis is occupied by 

 a cylindrical bone occasionally grooved. Remarkable peculiarities 

 exist in the intromittent organ of the marsupiata; in the opossum 

 the glans is bifid, and has three openings, one for the urine, and 

 two for the semen. In the ornithorhynchus paradoxus the penis is 

 double anteriorly, and in the hystrix, it divides into four glands, 

 each furnished with sharp papillse perforated for the discharge of 

 the semen, but in neither of these strangely organised animals does 

 the urine pass through it, this organ being concealed within the 

 cloaca. The urethra shall be deferred till the consideration of the 

 urinary organs. 



The female organs of generation in the mammalia consist of the 

 vulva, clitoris, nymphse, vagina, uterus, Fallopian tubes, and ovaries. 

 These latter organs are invariably double; in the marsupiata 

 their structure is racemose as in birds, but in all the other genera 

 they are more solid, and approach more or less the human type. 

 The Fallopian tubes present but few peculiarities, except in the 

 echidna and ornithorhynchi, where they experience a dilatation in- 

 feriorly to supply the place of a uterus, and afterwards open sepa- 

 rately into the short vagina, on each side of the orifice of the urin- 

 ary bladder. In the lower orders of mammalia the urethral and 

 sexual passages are blended together, the uterus is elongated in form, 

 and thin in its walls; in the carnivora, ruminantia, pachydermata, 

 and cetacea, a mesial cleft appears, and the cornua are greatly deve- 

 loped ; and in the marsupiata and most rodentia, the organ is 

 divided into two lateral halves, each opening separately into the 

 vagina, which, in the virgin state of the sloth, the ass, the mare, 

 the pig, and the cow, is divided by a narrow ve3itical septum. The 

 external organs of generation afford no striking peculiarities, except 

 in the deficiency of nymphae and hymen. 



From a review of the above details of the generative organs in 

 the marsupial and monotrematous orders, one must expect to find 



