portions are separated in the middle line by an intercalated little cartilage, or it may
be described as beginning at the right border of the trachea by two free ends or
pieces which enclose a cartilage at the middle and unite at the left wall of the tube.
The first piece on the dorsal surface begins at the right margin of the tube by two
free ends, lying, side by side, and which unite about the middle of the tube, the
single end just bending sufficiently round the left margin of the tube to form its
wall. On the ventral surface, the first cartilage has two distinct cartilages behind it.
The first is a small free cartilage opposed to its right third and terminating on the
right wall of the tube, but not enterihg into the formation of the dorsal wall. The
second lies against the two remaining thirds, but the cartilage passes right round
the left margin to their dorsal surface, and running obliquely backwards to the right
to the beginning of the first bronchus of that side. At its origin on the ventral surface,
it has a short portion bent back before itself, but this piece does not reach to the
left border of the tube (PL XXVIII, fig. 10). The first cartilage of the dorsal surface
has two behind it, overlapping each other in the middle line, but confined to its own
side of the trachea. The second cartilage of the ventral surface has two cartilages
behind it similarly arranged with regard to each other. The third dorsal cartilage
begins by a pointed end on the left wall of the tube, but soon divides into two halves,
which lie parallel and are confined to the dorsal wall. The fourth ventral cartilage
enters partially into the formation of the dorsal wall. Commencing at the right
side of the tube, it can be traced describing four spiral lines, but never encircling the
trachea, being almost exclusively confined to the ventral wall. I t receives a process
from the right of its commencement, and gives off two at the end of its first coil,
which pass on to a portion of the dorsal surface, the anterior lying behind the dorsal
prolongation of the second ventral cartilage; the posterior being prolonged beyond
it to the angle of divergence of the first bronchus and trachea. The rest of the
wall at the origin of the right bronchus is made up by small cartilaginous plates,
and a similar arrangement holds good at the point where the last bronchus is given
off; the ventral plates being generally bifurcated structures, only having a very
limited dorsal surface and sometimes enclosing small plates between them. On the
bronchi and their divisions, the cartilages are arranged in spiral rings, and on the
larger bronchi I have counted as many as five distinct coils in one cartilage. The
coils, however, are not simple, for secondary ones are given off, which are embraced
in the primary ones as'much shorter coils.
Lungs.—The pulmonary organs of Platanista as shown in Plate XXIX,
fig. 1, are there thrown apart, the better to expose the heart and its surroundings.
Each lung in the adult is 19*50 inches in length. When examined in the fresh condition,
its substance, as in others of the Whale tribe, is particularly spongy and
of a firmish texture. Both lungs are nearly similar in outline, and while they may
be described as single, or without marked division into lobes, the upper segment in
each is nevertheless marked by a shallow cleft, so as to warrant division into an
anterior and posterior lobe. The former, especially the left lung, has a well-marked1
semilunar marginal excision, which produces a rounded lobular promontory quite
in front ; the after division of the semilune being narrow and pointed on the left
side, and blunt and broad on the right side. The larger posterior lung division is
more uniform in contour, its hinder end being unequally emarginate and produced
on the right and left sides.
The entire inner borders of both lungs have irregular crenate edges ; in this
respect, in their partial segmentation, and in absence of lung bridge and superficial
pulmonary glands, differing from what obtains in Orcella (compare Pl. XXIX,
fig. 2).
Thoracic and JPulmonary Glands.—In mentioning the absence of superficial or
sternal pulmonary glands in Tlatamsta, it should be pointed out that glandular
masses similar in kind are not altogether wanting, but only they are placed deeply
at the root of the lungs, and at the base of the heart where they are attached to
the pericardium.
Among these glandular masses may be included what evidently answers to the
thyroid bodies. This pair of glands (Eig. 1, th) are of a bilobate figure and lie
across the trachea at an obtuse angle, where the trachea divides into right and
left bronchus. While joined mesially, each thyroid gland is egg-shaped, 1*75 inch
long and just under 1 inch in greatest transverse mid-diameter. They are smooth-
surfaced and dense in texture. Their intimate structure is of the usual vescicular
and colloid character appertaining to the ordinary constitution of these bodies.
Less prominent and more deeply situated than the aforesaid is a patch of much
smaller and quite irregularly sized and shaped glands {gl. gl. gl.). These dip between
the bronchi, extend among the great vessels at the root of the heart, and one long
narrow patch crosses the upper pericardial attachment, and sends finger-shaped prolongations
between the vena cava and aorta. Partially covering these, and with the
parts in natural position, somewhat overlying the thyroid bodies, there is also on
each side a very large superficial gland, between 2 and 3 inches long, and of a
kidney shape. Posterior to these and almost touching them is another rounder and
flatter, but equally large pair of glands, of a similar appearance to the last. Yet
nearer the apex of the heart and likewise attached to the pericardium in continuity
with the last—that is, adherent by cellular tissue—is a great broad glandular
mass of rounded outline. This dips both behind and in front of the heart almost
from root quite to apex. Other scattered nodules of a glandular • nature are
dispersed promiscuously on the surface of the pulmonary and pericardial serous
tissues.
I t seemed to me that all these glands may, more or less, be regarded as coming
under the denomination of modified lymphatic glands, whether bronchial or otherwise.
In a great measure they agree with the analogous glandular material met
with in Orcella (compare fig. 2, gl. gl., Pl. XXIX), and they also combine in part
the nature of the s*o-called pulmonary glands (p. gl.) of the latter animal. I t is
quite possible, nay probable, that portions of them may represent either remnants
of, or be, permanent Thymus glands ; but on this head I could not satisfy myself of
their identity in composition with the well-known foetal Thymus bodies.