With Figure 5.
The dissection has been made upon the same plan as the preceding Preparation of the urinary and generative organs of the male Rabbit, and it shows very clearly the exactness of the homology existing between the parts from the commencement of the urogenital canals, c and d, outwards. The two organs, b and b, in the two preparations are very closely similar, and this similarity has led to the belief that the uterus masculinus of the male Rabbit should be held to represent merely the vagina of the female. It is a sounder view probably to consider it, as stated above, p. 30, to represent both vagina and uterus.
The extent to which the vagina projects beyond the summit or. 'superior fundus' of the bladder is a remarkable point of contrast in the adult female Rabbit as compared with the adult females of most other species of mammals, placental and other; in the newly-born female however (in which it may be remarked the parts in question are curiously similar to the analogous and homologous ones of the male at the same age), these proportions are exactly reversed, whilst in well-injected adult specimens the superior vesical arteries are sufficiently obvious to remind us of their functions in foetal life.
The junction of the uteri, a, to the Fallopian tubes, at e, is marked by the difference in calibre of the two parts of the continuous and tortuous cylinders which they make up, and by the attachment to it of the 'l iga-mentu rotundum' which passes down to be inserted into the pubic eminence, as also of the 'ligamentum ovarii' and the 'broad ligament V The two uteri are entirely distinct from their points of junction with the Fallopian tubes up to their openings by separate ora tincae, one on either side of the rudimentary median septum on the anterior wall of the vagina, b. In the Bizcacha, Lagostomus trichodactylus, a South American Rodent with many points of affinity to the Marsupials (see Darwin, Origin of Species, p. 379, 6th ed. 1872), what is a rudimentary septum in the Rabbit forms a perfect division in the vagina for a distance of as much as one inch beyond the ora tincae, constituting thus a transition towards the arrangements characteristic of Marsupialia. (See Owen, P. Z. S. Part vii. 1839, p. 77.) The uteri are similarly distinct, forming a 'uterus duplex' in SciuruS) Arctomys, Spalax, Batkyergus, Echiniys, Erethizon, Hydrochaerus amongst Rodents, and in Orycteropus amongst Bruta; they fuse into a 'corpus uteri' with cornua uteri superadded to it at a greater or less distance from the commencement of the vagina, forming thus a uterus bicornis, in Mus, Cavia, Caelogenys, Dasyprocta amongst Rodents, as in most other placental Mammals; whilst even in the uterus simplex of Dasypus among the Bruta and in that of the Primates, more or less of the embryonal bifidity is retained by the production upwards and outwards of the angles of the fundus uteri towards the Fallopian tubes, much as are the angles of the uterus masculinus of the Rabbit shown in Fig. 4, b.
In the lower part of the vagina, a short distance above its junction with the urethra to form the urogenital canal (c), 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 Marsupials. 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, comprehending such widely different forms as Dasypus sexcinctus and peba, Brady pus tridactylus 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. crocuta (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 enclosure 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-stomus, 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, i, 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 crus of the clitoris, and in this specimen are smaller in size than the homologous glands in the other sex.
1 It is instructive to compare such a preparation as this of these ligaments with such a figure as that given by Dr. A. Farre (after Richard) in the Cyclopaedia of Anatomy and Physiology, Supplement, art. 'Uterus,' p. 598, fig. 404; or that given by Prof. Allen Thomson in Quain and Sharpey's Elements of Anatomy, ii. 1882, p. 707, fig. 608; or those by Henle, Handbuch der Menschlich. Anat. ii. ed. 2, 1873, figs. 364, 374, pp. 474, 487.