36 DESCRIPTIONS OF PREPARATIONS. 



the urethra to form the urogenital canal (V), two valvular involutions with 

 their concavities looking upwards are developed, and have been taken to 

 represent the somewhat similar projections in the double vaginae of Marsu- 

 pials. Similar folds exist also in the lower portions of the vagina of the 

 Rhinoceros and some other female Mammalia ; and in the upper of the 

 Cetacea, the Suidae, and the insectivorous Tenrec. The urogenital canal, c, 

 is laid open in part of its course, from the point where it commences at the 

 junction of urethra and vagina, and is seen to be of considerable length as 

 compared with the homologous segment in most Mammalia. This canal 

 appears to be of the greatest relative length in the Monotremata, where the 

 two uteri open into it separately and immediately above the openings of 

 the ureters and below the downward opening of the bladder, that is to say, 

 without the interposition of any vagina proper ; and of the least in the 

 Primates, where it corresponds simply to the Vestibulum vaginae. But the 

 morphological value of these facts is somewhat diminished when we find 

 that in an order with tolerably uniform internal anatomical arrangements 

 such as the Carnivora (to say nothing of an order such as the Bruta, compre- 

 hending such widely different forms as Dasypus sexcinctus andpeba, Bradypus 

 tridactyhis and Cholaepus didactylus), the length of this canal may vary 

 as much as it does in species as closely allied as Hyaena brunnea (Murie, 

 Tr. Z. S. for 1867, p. 504) and H. crocitta (Watson, P. Z. S. 1877, p. 376). 

 And in orders such as that of the Rodents as illustrated by the Rabbit 

 here, by Hystrix and by Dasyprocta, as that of the Insectivora as illustrated 

 by Erinaceus, and as that of the Prosimii as illustrated by one at least of 

 the Lemurida and by the Aye-aye, in which there is a urogenital canal of 

 greater or less length, we may find precisely the opposite condition set up, 

 that namely of entire separation of the genital and urinal canals, by en- 

 closure of the urethra within the lower part or corpus spongiosum of the 

 clitoris ; reversing thus the arrangement which is usual in female mammals 

 and is homologous to the condition known as ' hypospadias ' in males. 

 Thus in the females of the Norway Rat, Mus decumanus, as also in Lago- 

 stonius, Arvicola, Bathyergus, and Myodes amongst Rodents, Sorex and 

 Talpa amongst Insectivora, and Stenops, Tarsius, and some but not all 

 Lemurs amongst Prosimii, the clitoris is perforated by the urethra, and the 

 urinary and female genital canals are entirely distinct, which is not the 

 case here. One crus of the clitoris is seen here with its accompanying 

 muscle as cut away from the os pubis ; the bilobed termination of the 

 organ lies concealed within the vulva, with the inner walls of which it is 

 continuous. The ano-preputial glands, z, like the other organs from the 

 commencement of the urogenital canal outwards, correspond very exactly 

 with those of the male already described ; the glands representing the 

 Cowperian glands of the male, and known in the female as the glands of 

 Bartholini or Duverney, are seen between the ano-preputial glands and the 



