which in this aspect is a shade larger than either hinder extremity of the cerebral
hemispheres. The medulla spinalis is relatively large, and set high in relation to
the cerebellum.
Erom the foregoing description it would seem that Orcella has a delphin-
oid form of brain, comparatively massive, broad, and although in a general way
flattish, yet by no means low set. The fronto-orbitai lobes are unusually deep, and
the anterior brain-facies altogether vertically abrupt in contour. The cerebellum
is preponderantly large and in a great measure uncovered both laterally and above.
Moreover, as the sequel will show, the brain of Orcella manifestly differs in several
particulars from that of Platanista, while it strikingly follows the general shape of
that of Globicephalus.
External organs of generation (Plates XXXIII and XXXIV).—The cleft of
the vulva resembles that of other Cetaceans, the skin around being somewhat
smooth and pale coloured. The most characteristic feature is the existence of the
well marked perinseum (pe.) already mentioned, the raphe being about 1^ inches
long, and in this particular, Orcella essentially differs from those whales which,
being destitute of pelvic bones, have no perineal space.
The ma/mmary slits (Plate XXXIII, fig. 1 ni) are each 0‘70 inch long and
situated T20 inch from the vulva, their hinder ends being 2‘20 inches distant
from the anus. The nipple is not prominent, being laterally compressed and
placed at the base of the mammary furrow which is comparatively shallow, viz.,
0-20 inch deep.
The mammary gland {mg.) has an enormous dilated lactiferous sac, 2 inches
■ long, with a position immediately underneath the nipple. I t runs horizontally •
forwards, and into it all the lactiferous ducts open. The other portion of the gland
is very solid in character, flattened along the middle line, and in area has a length
of 9-50, a breadth of 3’25, and 0-25 of an inch thick. I t is invested by a
strong fibrous capsule which is very firmly adherent to the gland substance, and is
with difficulty removed from it.1
The vagina (®) has the usual Cetacean characters, and has six os tincæ. I
did not observe in the’ vagina of the gravid female any of those remarkable glands
which I shall have to describe in the gravid vagina of Platamsta.
Gravid uterus.—^The mouth of the true os is a little to one side, which also holds
good with the lower os tincæ, thus conferring a slightly spiral arrangement on the course
of the canal. The true os, when viewed from the uterine aspect (Plate XXXIII,
fig. 2), appears almost smooth, with only a few rudimentary folds, and in this respect
it materially differs from the os uteri internum of Platanista (Plate XXXI, fig. 2),
and the Narwhal.2 In the gravid female the foetus was developed in the left horn, and
1 See Hunter, I. c. : Kuhn, Férussac, Bullet, des Sc. N at. 1830, t. xxii. p. 322 : Rapp, Meckel’s Archiv. fiir. Anat.
1830, p. 358 : Die Cetaceen Zool. Anat. dargestellt, 1837, p. 178 : Trail. Edinr. New Phil. Journ. 1834, Vol. xvii. pp. 117
e t 363: Is-Geoff. St. Hilaire, Ann, des Sc. Nat. 2Ser. 'Zool. t. 1.1834, p. 174: Jacob, Brit. Assoc. Report* 1835,
p. 86: Astley Cooper, Anat. of Breast, 1839: H. Milne-Edwards, Leçons, sur la Physiol., t. » .1 8 7 0 , p. 124, and
Turner, I. c.
* Turner : Lectures on Placent. 1876, p. 50.
it is worthy of remark that the majority of Cetacea hitherto observed in utero have
been developed in the same horn. This foetus I removed with my own hands, and I
am therefore in a position to say that its relations to the uterine wall were the same as
those which obtained in Platanista, under which species the uterine and foetal relations
will be fully described. The uterine walls, at the full period, are however, much
thicker tba.n those of Platamsta (Plate XXXY, figs. 4 and 9), and the mucosa is
much more spongy, and the crypts more numerous and much more regularly distributed
than in that genus. Scattered among the crypts there are considerably larger
infundibuliform orifices, and moreover the entire surface of the mucosa is not cryp-
tose. A long narrow bare surface commences about 6 inches from the uterine orifice
of the left Eallopian tube, and continues along the lower wall of the fecundated horn
for about 3 inches beyond the point where the horn bends on itself at the septum.
In one instance in Platamsta this bare area occurred ; whereas in another and more
matured uterus it was absent; the nude surface of-the chorion being present in both
cases. I have not observed it in the Bactrian camel, and no trace of it is visible in
the uterus of a Tapir, the foetus of which was nearly fully mature, and the chorion
of which had this area, free of villi, enormously developed. Besides this elongated
tract free of villi, a very limited area occurs at each Eallopian pole of the two horns,
and which has been figured at Plate XXXIII, fig. 3 f. This bare surface however,
appears more properly to belong to the mucous surface of the Eallopian tube itself
than to the uterine cavity.
The bare or non-cryptose areas which have been described,—namely, the smooth
surface at the os uteri internum, the long tract free of villi following the course of
the locality of opposition of the umbilical vessels after they divide on reaching the
chorion, the very limited bare surface of a doubtful nature at the Eallopian
orifice of each horn,—would appear to differ structurally from the following bare
surfaces.
Smooth spots.—The whole of the inner surface of the uterus, right and left horns,
is irregularly studded over with smooth spots free of cryptose structure. The spots
are of various shapes, but they generally have a more or less rounded appearance but
are of different sizes, varying from 0'05 to 0’20 of an inch in diameter. They form
denser groups in some places than in others. Even with the naked eye when
a good light is allowed to fall .at an angle on the uterine surface, I could detect what
appeared to me to be an orifice in the centre of many of these smooth spots, and this
I have also observed in Platanista and to a much more marked degree on the
uterine surface of the Camel and Tapir, but only to a very limited extent on the
uterine mucosa of Manis.
The surface of the fecundated horn is thrown more or less into rugose folds,
which tend to radiate from the point where the horn bends on itself opposite the
s e p t u m w h i c h divides the two horns, but they are not well marked except àt the
point indicated, and in the neighbourhood of the surface of the Eallopian tube from
whence they radiate longitudinally. Rugose folds also occur in the long axis of
the portion of the cavity immediately above the os uteri internum. In the unfecun