480 CETACEA. 



way, while the two latter constituted broad folds, which were persistent in the enlarged 

 vagina of the pregnant female. Besides these there are some other, but much smaller, 

 folds around the opening. At the middle of the canal there is a strongly marked 

 cross fold (PL XXXII, fig. 1, of) on the ventral aspect, with some short oblique 

 creases at its sides, and a short transverse fold before it. The first-mentioned limits 

 anteriorly the longitudinal folds that arise at the opening of the vagina, and it can 

 be detected in the vagina of the gravid female. The dorsal surface of the canal 

 has only a few feeble longitudinal folds, and the area immediately before the 

 transverse furrow of the ventral surface is perfectly smooth, but anteriorly to this 

 occur the three or four great permanent folds, the os tincm, characteristic of Cetacean 

 vaginsB. The first two of these folds are quite smooth, but the third has generally 

 its mucous membrane thrown into twenty to twenty-two thin secondary leaf -like 

 folds, and in this respect it closely resembles the os uteri externum, which is covered 

 with similar lamellae more perfectly developed, and which are more or less conti- 

 nuous with others which occur on the os uteri internum itself. At the free margins 

 of this the third fold and of the os uteri externum these lamellae are bent upon 

 themselves, and in the gravid uterus they are converted into very thin overlapping 

 leaves. The appearance of the vaginal folds and the character and distribution 

 of the lamellae in the virgin are shown in fig. 1, PI. XXXII, while at fig. 2, 

 PL XXXII, is a representation of the inner orifice of the os uteri internum in the 

 gravid female. The long axis of the entrance to the womb is directed obliquely 

 forwards slightly to the left, but the uterine orifice is to the right of the middle line. 

 The body of the uterus, which is 0*65 inch in length, is curved first to the left and 

 then to the right side, so that the orifice of the left horn is brought into the same line 

 with the OS uteri internum, while the opening to the right horn lies external to it. 



Owing to the oblique position of the vagina, and consequently of the uterus, 

 the left horn also lies at a lower level than the right. These relations of the parts 

 in such cases would seem to be conducive to the fertilization of the left horn in 

 preference to that of the right, which is placed at a higher level and eccentric to the 

 OS uteri. 



In the unimpregnated uterus (fig. 3), the horns bend backwards towards the 

 organ, until they are on a level with the ovaries. The walls of the common cavity 

 of the uterus (fig. 1, u) become thickened as they approach the horns, and the 

 lamellae of the mucous surface become swollen into rugae. The mouths of the 

 horns are large enough to admit a crow quill, and they are separated from each 

 other at their commencement, for about 0*65 inch, by the common septum, the free 

 margin of which constitutes their inner lip. Their inner surfaces (/) are covered 

 with from six to seven prominent longitudinal folds, usually terminating at their 

 mouths in free ends, although they sometimes there unite. At the angle where each 

 horn bends backwards on itself the mucous fold which passes over its induplication 

 forms an angular projection inwards, and the rugae or folds converge to the opening 

 of the Eallopian tube, where they terminate. The right horn is 1-75 inch long, and 

 the left 1'65 in length with a diameter of 0*36 inch. 



