example the double innominate trunks, and the left of these has a similar subclavian,
and long parallel carotids. The outer carotid about its middle sends
inwards or mesially a small pharyngeal branch and in the opposite direction a
cervical branch, the main vessel itself passing below the hyoid arch. The inner of
these parallel carotids, in its way towards the head and at unequal intervals, sends
several branchlets towards the middle line of the neck, and itself passes above the
hyoid. Besides a left vertebral artery and thyroid axis, a considerably sized and
deeply situated branch appears to issue from the subclavian. This left deep
cervical, post-thoracic, or superior intercostal, goes to form the rete mirabile lying on
the inside of the chest. The chief differences on the right side of this foetus as
compared with the preceding adult are its wanting a separate axillary artery derived
from the right innominate, the right being, like the left axillary, an offshoot from
the subclavian, and the subclavian yielding at its root a branch apparently representing
a superficial cervical.
Compared, therefore, with the vascular distribution in Globicephalus, the variations
in Orcella seem to be as follows
(a). The proximity of the two main trunks arising from the aortic arch, these
main vessels being wider apart in the Pilot Whale.
(fi). No long “ carotis facialis” (Turner) or median third carotid branch from
the right subclavian.
(<?). The deep cervical on the right springing from the innominate in Orcella,
whereas it has a carotid origin in Globicephalus.
The brain: Its configuration.—Whilst the condition of the carcass of the
full-grown animal permitted of many of the organs being fairly examined, such
was not the case with the brain. I t had become so softened, and its parts so fallen
asunder, that it could not be properly examined. Its shape, however, was ascertained
with tolerable exactitude by means of a cast of the cranial cavity in plaster
of Paris. Plate XXX, figs. 4, 5, and 6, represent this cast from an upper, a lateral,
and a basal view, half the diameter of the original.
The measurements of the brain or rather of the interior cranial cast are as
undemoted :—
Inches.
Greatest antero-posterior length (prominence of frontal lobé to post-cerebellar protuberance) . 6’40
Greatest breadth (viz., temporo-occipital region) . . . 5'85
Diameter at the middle of frontal region in front of Sylvian depression . . . 5'40
Greatest height (ironto-parietal region) ^ • . . ■ • . . . 4‘00
Extreme length o f each cerebral hemisphere . . . . . . . 4‘35
Cerebellum in antero-posterior diameter, about . . . ■ . . • 2 -20
Cerebellum extreme breadth, about ^ 4 ‘10
Vertical height o f cerebellum . . . . . . . . . 2*60
Although the brain was somewhat disintegrated, I was able to determine that
it was highly convoluted, like what we find in other Cetaceans.
Viewed from above (fig. 4), its breadth as compared with its length in the
cerebral hemispheres is remarkable, this being in round numbers as 6 is to 4£.
The longitudinal fissure is a deep and wide cleft, with both its margins rounded off,
leaving a wide interval between the lips of the frontal and occipital comers.
A very considerable surface of the cerebellum is thus exposed superiorly.
The anterior face of the brain presents a massive appearance, both breadth
and depth being conspicuous. The supra-orbital region is specially prominent.
What corresponds to the optic nerve tract presents a moderately marked vertical
ridging situate about the middle. This front surface of the brain is relatively
truncate and flattish as a whole.
The profile or lateral aspect (fig. 5) of this brain mould shows, not only the
cerebellar exposure, but that the cerebellum is of a good height, and that thè
cerebrum is much deeper in the frontal than in the occipital region. The outline
of the cerebral hemisphere from this point of view is kidney-shaped, the infraorbital
region fullest, and the Sylvian fissure shallow and only noticeable low down.
A rim of projection at the margin of the post infra-occipital sweep, and a semilunar
ridge facing this, on the surface of the cerebellum, mark the depressions excavated
in the bone for the large venous sinuses. The root of one of the branches of the
5th nerve stands well out, and the elevation of the orbital nerve (as alluded to
on the anterior face) crops forward beyond the supra-frontal margin. If a vertical
line be drawn giving the extreme limit of height of the cerebrum (which is in
front of the Sylvian fissure), and another horizontally at right angles to this
giving the extreme length of the cerebral hemisphere, these would show but a
slight preponderance in favour of the latter. In other words, depth and breadth
are characteristic features of this brain, but the latter, as shall hereafter be
shown, is the distinguishing and most obvious difference between it and that of
JPlatanista. - The figures in Plate XXX, however, do not afford a fair comparison,
as those of. JP. gangetica are representations of the brain itself, whilst those of
Orcella are from the mould of the cranial cavity.
As in : the upper surface, the base of the brain (fig. 6) is of great breadth,
and the cerebellum is seen to cover a considerable area. Ìbis surface, moreover,
taken as a whole, is remarkably flat, but especially so in the extensive figure-of-
eight boundary formed by the infra-orbital regions, pons and cerebellum. A raised
median, transversely oval portion, possibly indicative of a good-sized flocculus, is
noticeable on each half of the cerebellum.
With regard to the nervous trunks, their great thickness, so far as this cast
is concerned, is apparent rather than real, inasmuch as they give the capacity
of the foramina and basi-cranial grooves ; for, as is well known in Cetacea, the
nerves are'accompanied by accessory vascular plexuses and thick sheaths giving
increment of bulk other than what is due to. the nervous cords themselves. I t
may be remarked, however, that the 5th, 6th, 7th, and 8th pairs possess a magnitude
corresponding to the functional importance of these nerves in the whale
group.
Viewed from behind, the brain cast displays the occipital borders of the cerebrum
obliquely pitched, and covering and overlapping outwardly the cerebellum,