Chevron hones.—These structures begin between the 34th and the 35th
vertebrae, and the first consists generally of two bones not united in the middle line,
but articulating by two surfaces to the anterior and posterior borders of the 34th
vertebra, and from the circumstance that it is so connected to the vertebra it would
appear to consist of two pairs of bones united. In the next pair the bones of the
opposite sides are also separate, but in all the succeeding bones, as far as the 19th,
they are united, and each forms an arch across the vessels, but beyond that point
they are again resolved into two. They attain their maximum development between
the 43rd and the 44th vertebrae.
Ribs.—The ribs are transferred to the transverse processes at the 8th dorsal,
and in this respect Orcella differs from Globicephalus and Orca, in which the 7th rib
is not attached to the body of the vertebrae, but is wholly transferred to the transverse
process. The one or two pairs of free ribs lie in the muscles of the side at a considerable
distance from the vertebral column. There are nine well ossified sternal ribs,
and five of these on each side are applied to the side of the sternum. The first
rib is articulated to the anterior external angle of the sternum. The ribs conform
to the characters distinctive of the Delphinidce.
Sternvm.—This bone has the general features characteristic of the sternum of
the Relphmidce, with an emarginate anterior border, the bone attaining its greatest
breadth behind the attachment of the first rib, where it outwardly dilates into
two processes, most marked in O. jltminalis. The anterior border is notched in the
latter species, but in O. brevirostris the primordial fissure has closed anteriorly, but
enclosing a rounded imperfection of ossification distinctive of many Cetacean sterna.
In the hinder end of the bone, the remains of the primordial fissure may either be
indicated by a deep notch, as is generally the casein O. fiuminalis, or by a groove in
O. brevirostris. There are no traces of ossified mesostemal segments.
The sternum of the gravid female of O. brevirostris retained its original twofold
nature, being mesially divided into two halves, and only two ribs were
attached to it, and that unsymmetrically, the left being considerably anterior to the
right rib.
Rectoral limb : .Scapula.—*This bone has more antero-posterior extension than
in either Globicephalus, Orca, or Rhoccena, and is especially distinguished from the
scapulae of these g e n e r a by the broad sweep of the supra-scapular border and the
downward arching of the coracoid and glenoid borders, which are of nearly equal
length, their angles being nearly in the same plane. The acromion is long, narrow,
and slightly downwardly curved.
Su/merus, radi/us, and ulna.—These bones do not call for any special description,
as their forms vary but little in the Cetacea, but it may be observed that the
humerus is relatively longer than in Orca, having more the proportions that this
bone bears to the other bones in Globicephalus. The same is also true of the radius
and ulna.
Mcmus.—The second finger is the longest, and is relatively longer than the
corresponding finger in Orca, and considerably relatively shorter to the rest of the
limb than in Globicephalus, the proportions of the fingers to one another being much
the same as in Orca, there being not that marked difference between the length of
the 3rd and 4th finger that distinguishes Globicephalus. The whole length of the
arm from the end of the humerus to the tip of the 2nd finger in the dried limb of
a female O. brevirostris is about one foot, of which the 2nd finger measured
from its carpal bone is 6 inches, the humerus being 3"*62, the radius 3"-50, the ulna
3 inches, and the carpus at its middle 1"'40. The greatest breadth of the distal end
of the humerus is l"-70, and the greatest breadth of the radius 1"'80, the combined
breadth of the forearm proximally is 3"*32.
In the carpus four bones are in contact with the ends of the radius and ulna,
two in opposition to the former and two to the latter, with another bone opposed
to the metacarpal of the 2nd finger. The small bone which is opposed to the
outside of the most external of the ulnar bones is evidently the metacarpal of the 5th
digit. The bone placed between the end of the radius and the metacarpal of the
1st digit is the scaphoid ; the other bone touching the end of the radius and also a
portion of the ulna is undoubtedly the intermedium, and the bone on the outside of
the nlnn. the cuneiform or ulnare. Lying between the os intermedium and ulnare is
another bone, which also touches the ulna, but which appears from its position
to be the cuneiform, although it may probably be of a two-fold origin. There is
a large space at the base of the 3rd metacarpal unoccupied by any bone, and which
marks the position which the os magnum should have occupied. The bone applied to
the extremity of the second metacarpal is the trapezoid. The manus has thus five
bones in the carpus, three belonging undoubtedly to the first and two to the second
row.
In the 1st finger there may be either one or two phalanges» the terminal
phalanx being a mere ossicle ; in the 2nd finger there are five or six phalanges, which
are as broad as long ; in the 3rd there are three ; in the 4th two, and in the 5th a
phalanx may be represented by a single ossicle or by cartilage only. The metacarpals,
five' in number, vary considerably in form. That of the 1st finger is a squareshaped
bone ; that of the 2nd is a little longer than broad ; that of the 3rd is
twice as long as broad ; that of the 4th has its breadth equalling its length ; while
that of the 5th is quite as rudimentary as the first bone of the series.
The pelvic bones.—All the facts which I have been enabled to ascertain regarding
the pelvic bones of this genus have been already stated under O. Jluminalis and,
in the preceding pages, with the exception that the termination of the intestine
lies between the posterior ends of the bones and is attached to them by a strong
fascia. There are no accessory bones.
Skull.—The skull of O. brevirostris has been described by Prof. Owen1 in
detail. The length of the palatal surface of the maxilla which represents the
length of the back of the skull is very slightly shorter, or equal to the interval
between the inferior border of the foramen magnum and the posterior borders of
the palatal surfaces of the maxillaries. The osseous beak is slightly contracted a