encircles the tube, but its two ends do not meet. Posteriorly it gives off an offshoot
which runs from right to left, appearing on the ventral surface of the left border of the
trachea. The fourth is a short cartilage on the right side of the ventral aspect of the
tube. The fifth encircles the trachea, though its ends do not unite, hut overlap each
other, and the anterior border of its dorsal portion gives off a short offshoot to the left.
The next ring nearly twice encircles the trachea, above and below the point at which
the right bronchus is given off. I t commences in a free end on the left border, and
after describing the course I have indicated unites with itself on the dorsal surface,
where it gives off two short branches directed backwards and to the right. The right
bronchus is attached to the projecting third of the fifth ring of the trachea, and it
commences by a cartilage which twice encircles the tube, but describing its first
round in a zigzag manner, leaves a vacuity at the inside of the tube which is opposed
to the trachea.. The method of division and distribution of the fifth cartilage is that
which prevails on the main bronchial division. In the first part of the trachea the
cartilages are round and cord-like, but as they are traced backwards they become
relatively broader and flatter, yet thicker than those of Plata/nista, and are separated
by rather wide intervals, so that the tube has considerable expansibility. The first
bronchus is 4’ 50 inches long before it divides. The other division is as capacious
as the left bronchus, and runs 3 75 inches before its division. The left bronchus is
2*50 inches from its division to its bifurcation.
Lungs (Plate XXIX, fig. 2).v^Tn the adult the base of the right lung,
instead of being pointed as in the left, is bevelled off obliquely from its outer
to its inner margin. The anterior border in its upper third is hollowed out
for the reception of the heart. Two small lappets above this portion overlie
each auricle, and the apex is only 3 inches above the arch of the aorta. The
extent of lung posterior to the apex of the heart measures 12-50 inches in length by
5*25 inches in breadth, while the total length of the organ is only 19 inches, so that
the great mass is posterior to the heart. This portion is concave anteriorly, and
corresponds to the convex surface of the liver, over which it lies, but separated by the
interposed diaphragm, and the dorsum of the lung is of course convex. The apex
has two rounded angles separated by a concave interval, and its total breadth here is
5 inches; the posterior angle being twice as large as the anterior. Below the heart
the two lungs appear to. approach eaph other much more nearly than in reality,
from the circumstance that the lower end of the cardial border of the lung is the
seat of a large gland {Pgl.) which projects towards the middle line along the diaphragmatic
attachment of the pericardium.
In the foetus the apex of the lung is rounded without any angles; the base of
the right lung is not bevelled off, but partially divided into two lobes.
Pulmonary glands1 (PI. XXIX, fig. 2 Pgl., and PI. XXXVII, fig. 5).—In the
adult the pulmonary gland is largest on the left side. I t is a triangular body l"-50
1 Pulmonary glands, evidently of a kindred sort, have already been recorded by Hunter, as obtaining in Delphinus
tursio; and in specimens of Olobiceps inhabiting the Chinese, American, and British eoasts, respectively, by Williams,
Jackson, Gulliver, and Marie. In Risso’s Grampus also they have been met with by the last-mentioned observer, who,
moreover, has discussed their nature, and given figures of them, in position, in his Memoir on the organisation of the
Ca’ing Whale already cited.
long by 1"*0 in breadth at its base which is directed anteriorly. I t is attached along
the external border of the lung from below the pericardial attachment and from the
anterior margin of its base. A-process, 2 inches in length, is sent upwards along the
pericardium, and another process passes inwards under the pericardium as far as the
inferior vena cava on the right side. The said gland consists of two irregularly
shaped masses, one of which is applied to the internal margin of the lung, and has a
process prolonged upward from it along the pericardium as on the opposite side, and
the other lies internal to the former mass, and reaches to the side of the vena cava.
The portion of the gland which runs inwards towards the vena cava, and the
process prolonged up the pericardium are traversed by an enormous vein, which
when opened has a capacity of 0*9 inch throughout its course. The veins of the
two sides open by a common orifice into the right side of the inferior vena cava
immediately below where it reaches the heart. The left vein is thus twice as long
as that of the right side, and it arches slightly upwards near its termination, so that
its orifice is placed nearer the heart than that of the left side. The vessels, as they
bend round the base of the gland of the left side and traverse the double glandular
mass of the right lung, give off numerous fine branches to the glands, and, running
about two inches along the pericardium, they are found to proceed from the walls
Of the chest, being projected off the sternal portion of the cavity on to thè pericardium.
At this point they are in close relation with the internal mammary artery
(fig. 2, m.), which leaves the pericardium from the thoracic wall at the point where
they reach the latter structure. I never have had an opportunity of examining carefully
the larger vascular plexuses, which exist along the vertebral column of this
dolphin and in its intercostal spaces, but the origih of this large venous trunk from
the chest would render it probable that its chief function was to relieve the venous
plexuses by affording their blood a short and direct channel to the heart, and thus a
more frequent flow than they would possess had the blood to travel a greater distance.
The object of this would seem to be to confèr great functional activity on
the respiratory structures of the chest, which it is necessary should perform their
functions reliably, so to speak, and well.
Minute structv/re o f pulmonary glands.—In treating of the pulmonary organs
of Plata/nista gangetica, I shall have occasion to pass under review certain
glandular structures analogous to those under consideration. In illustration of
the tissues in question, I have figured on Plate XXXYII, fig. 5, a portion of
the gland of Or cella, and at fig. 4 a part of that of Platamsta. These sections
drawn under a low microscopic power make obvious the resemblance of their
intimate structure. The main substance of the tissue is composed of a retiform
mesh-work (r.), in the interstices of which are closely packed cells (fig. 4, c.) of the
diameter and appearance of lymph corpuscles. The finer threads of connective
tissue in some places are as delicate as a spider’s web, in others thicker, almost
membranous in consistence ; the two kinds forming a great variety in the dimensions
and figure of the areolae. Scattered about are much larger open spaces, quite
irregular in contour and in thickness of walls. These evidently are transverse