l i
Fig. 2. The interior of the larynx of Qrcella brevirostris, of natural dimensions.
By a vertical section the posterior wall of the chamber has been slit up
and the opposite moieties everted, the anterior, lateral walls and bottom
of the cavity, therefore, appear only to be those displayed: e., epiglottis;
a., arytenoid cartilage; <?., cricoid in section; an., arytenoideus muscle in
cross section, on the right side, almost or as if continuous with (cap),
the erico-arytenoideus posticus; v,, a vascular meshwork enclosed within
fibrous tissue and superficial to the preceding structures; s. refers to
the multitudinous sacculations, both forming the floor and anteroinferior
laryngeal wall: a raised septal band occupies the median line
continuous with the main radial septse of the floor.
„ 3. A view (natural size) taken as far as the middle line of the right side and
from behind of the lower part of the tubuliform posterior nares of Plata-
nista. A segment of the protruding glottis is seen behind, to the right
and front of which the opened posterior nares show orifices of the eusta-
chian tube. This latter has a remarkable grooved and saccular character,
some of these representing communicating canals split u p ; diverticula
being obvious : ph., cavity of pharynx; e„ epiglottis; a.» arytenoid cartilage
; p. n., posterior nares; eu1., eu2., eustachian canal \ d., diverticulum.
„ 4. A sketch, also of natural size and from the same animal, of an eustachian
dilatation. As in fig. 3, it likewise is the right side, but from a different
point pf view, viz., interiorly looking into the passage from the gular
sac prior to its opening into the posterior nares; t. indicates a tendinous
cord passing from wall to wall.
„ 5. Another view of the eustachian sac of the P. gangetioa, natural size. This
is on the left side, and also exhibits the characteristic septa sacculations,
ramifying channels, and chordae tendinese,
„ 3. Anterior or under surface cartilages of the right moiety of the larynx of
Platanista, Reduced to fth natural size.
„ 7. Posterior or upper surface of same, fth natural size,
„ 8. Under surface of larynx of Qroella brevirostris, its right half reduced -k
natural size,
„ 9. Posterior or upper surface of fig. 8, also ^ natural size.
„ 10. A ventral view of portion of the trachea of Platanista gangetioa, of natural
dimensions. The peculiarities of the cartilaginous rings as described in
the text are here accurately displayed.
„ 11. A portion of the trachea of Qrcella brevirostris, likewise natural size and
same aspect as preceding.
PLATE XXIX,
Fig. 1. Lungs, heart, and great vessels of Platanista, ^rd natural size,
„ 2. The same parts in Orcella brevirostris, but somewhat more in natural position,
also reduced to £rd natural size. Similar lettering applies to each
figure: 1., lung; d., diaphragm; pc., pericardium; r. v., right ventricle;
I. v., left ventricle; r. a., right auricle \ I. a., left auricle; p,f pulmonary
artery; ao., aorta; v. o., vena cava; g. I., enlarged patches of lymphatic
glands; Pgl., special pair of pulmonary glands} t, h., thyroid gland; tr.,
trachea; p. n. pneumogastric nerve; m., internal mammary artery.
PLATE XXX.
Fig. 1. Upper view of the brain of Platanista, of natural size, and showing
a symmetry of the cerebral lobes and convolutions.
„ 2. Right lateral aspect of the same brain.
„ 3. Base of the brain of Platanista. 2, optic nerve, only a minute thread;
5, 6, 7 and 8, corresponding nerves of right side; p., pituitary body;
a., the corpora albicantia; pv., pons varolii; M., medulla oblongata; t.,
temporal lobe; sy., sylvian cleft,
„ 4. Mould of the brain cavity of Qroella brevirostris, Owen, ^ its natural
magnitude, and seen from above,
„ 5. Left lateral face of same cast of the brain cavity.
„ 6. Its basal aspect with impressions of some of the cranial foramina for nerves
and vessels extant.
PLATE XXXI.
Fig. 1. The external genital region and foetus within the left horn of the uterus
of Platanista gangetioa. Drawn to scale |r d natural size : a., anus,
the genital slit apparently continuing forwards from it ; m., mammary
orifice ; o., ovary ; f , fallopian tube ; fm., its fimbriated extremity ;
p., pavilion ; am., amnion ; c., umbilical cord ; t., tail of the foetus twisted
in a comer of the sac ; h. points to the minute hairs on the muzzle
which afterwarwds are lost ; e., eye.
„ 2. A view of the folds from the os uteri internum of a gravid Platanista,
reduced frd natural size.
„ 3. A portion of the inner wall of the uterus of P. gangetioa showing at f . the
entrance of the fallopian tube. Drawn to natural size.
PLATE XXXII.
Fig. 1. A virgin uterus of the Gangetic Dolphin, laid open from behind; natural
size: v,, vulva dragged apart; va., vagina; of. of.* cross and oblique
folds j os.t os uteri externum, with sections of thick mucous folds
beneath; u., cavity of the u te r u s f ., horn of uterus opened; o., right
ovary; r., rectum.