division of the tubercle, to the vertebra which forms the first of
the coalesced series of sacrals; and the body of the rib, instead of
preserving the regular outward curve of the antecedent ones, is more
suddenly bent soon after it emerges beyond the margin of the ilium; the
lamelliform part thence continued is straighter, and, moreover, shows
upon its outer surface a flattened facet, indicative of pressure or
friction by the movements to and fro of the thigh over a rib in such
position. Beyond this surface the rib curves in a way not shown in the
other specimens; the distal end has the flat syndesmotic articular
surface to which had been attached a hæmapophysis not reaching the
sternum. In this last (eighth) free rib there is no epipleural process,
nor any definitely marked ligamental surface on the posterior margin
indicative of the attachment of such process.
The body of a posterior vertebral rib (Pl. IV. fig. 10) shows a
fracture which has been healed, with some irregular ossific deposit on
the inner surface. All the ribs have a pneumatic foramen (ib. figs. 2,
7, 8, _p_) at the fore part of the neck, near the base of the tubercle.
The eight left vertebral ribs (Pl. III.) and the five right ones do
not, either of them, constitute a consecutive series, but have come
from different individuals, of different sizes, as exemplified in the
third rib figured in Plates III. and IV.
The sternal ribs (P. IV. figs. 3 & 12) are characterized by the two
facets, nearly or quite meeting at an open angle, into which their
sternal end expands (ib. fig. 3, _c_). One of these ribs, which is
entire, shows the single, elliptic syndesmotic surface at the opposite
end (ib. _b_); it is 3½ inches in length, with a greatest breadth of 5
lines, and is straight. Another and longer specimen (ib. 12) shows a
moderate degree of curvature. A third specimen is 6 inches in length:
the proximal end has a breadth of nearly half an inch (the penultimate
rib in Pl. III.).
Five successive sternal ribs are indicated by gradational size and
curvature, and a sixth, which does not reach the sternum. Before
describing this bone I shall proceed with the account of the sacral
vertebræ, and the expanded hæmal arches of such as complete the pelvis.
_Pelvis._ (Plates III. & VII.)
The pelvis of the Dodo is chiefly remarkable for the flatness and great
breadth of the posterior half, corresponding with the characteristic
proportions of that part of the body in Pl. I. fig. 2, and in the old
woodcuts of the Dutch “Dodaersen”[25]. It includes sixteen coalesced
sacral vertebræ, with which the iliac bones are continuously confluent.
The first sacral shows the transversely extended and concave articular
surface of the centrum (Pl. VII. fig. 1, _c_); the subcircular pit (ib.
_p_) for the head of the rib is behind the middle of the side of the
centrum, at its upper part; the inferior surface is ridged lengthwise;
and a transverse low but sharp ridge defines the posterior boundary,
the depressions in front of which indicate the hindmost origins of the
subvertebral muscle (longus colli?). The anterior outlet of the neural
canal (ib. _n_) is subcircular in one specimen, vertically elliptic in
others, and 3 lines or less in transverse diameter. From the sides of
the neurapophyses stretch out the strong buttresses of bone which blend
with the under part of the ilia, giving off from the fore part of their
base the præzygapophyses (ib. _z_), and from the back part of their
apex the surface (ib. _d_), or part of it, for the tubercle of the last
moveable rib, the ilium in the latter variety affording the rest of
that surface. The fore part of the strong neural spine (ib. _ns_) is
roughened by a syndesmotic surface; it rises to a height of 14 lines,
curving forward, and is confluent at its summit with the approximated
anterior margins of the ilia. A continuous track of bone, forming a
smoothly obtuse longitudinal ridge, represents the summits of the
succeeding sacral spines (ib. fig. 2, _ns_) to the hindmost vertebra
of the series, without any trace of their primitive division; but this
track rises, posteriorly, above the shallow channel on each side, in
which are the foramina (ib. _o_), indicating most of the constituent
vertebræ.
The second sacral vertebra abuts against the ilium by a pleurapophysis
(ib. fig. 1, _pl_ 2), as well as a diapophysis (ib. _d_ 2); but the
former is a slender, straight filament, or narrow plate of bone,
confluent at both ends.
In the next two vertebræ the pleurapophysis (ib. _pl_ 3 & 4) assumes
more breadth and robustness, but is short and straight, abutting
against the inner surface of the ilium an inch in advance of the
acetabulum. The first of these rib-buttresses inclines forward, and is
completely confluent with the ilium; the thicker one (ib. _pl_ 4) has
retained part of its primitive ligamentous attachment to the ilium: the
proportions of both are subject to some variety.
These are succeeded by three or four vertebræ in which the
pleurapophysis is not developed, the attachment to the ilia being
by diapophyses only (ib. _d_ _d_), which are short slender lamellæ,
directed upward and backward; below and between them are the double
orifices for the separate motory and sensory roots of the sacro-spinal
nerves. In the next vertebra the pleurapophysis (ib. _pl_ 8) reappears,
longer but more slender than in the fourth sacral, extending obliquely
backward, and expanding at its extremity to abut against a prominence
on the underside of the ilium, opposite the hind part of the
acetabulum, with which prominence the rib has completely coalesced by
an expanded end. The under part of all these vertebræ is traversed by a
sharp median longitudinal ridge, which is more feebly and interruptedly
continued to near the end of the sacral series.
Eight vertebræ, abutting by diapophyses only (Pl. VII. _d d_) against
the ilia, succeed the one last described; their coalesced bodies are
less than half the breadth of those of the preceding vertebræ: they
gradually diminish in depth to the last, without loss of breadth. The
diapophyses proceed obliquely outward and backward, are lamelliform,
about 9 lines in length, and intercept oblong cavities of the same
extent and direction, into which open the orifices (ib. fig. 2, _o_)
noticed on the upper surface of that part of the pelvis. The articular
surface of the body of the last sacral is transversely elliptic, 4
lines by 2 lines, and very slightly convex. The outlet of the neural
canal, above it, is circular, and about a line in diameter, the whole
vertical extent of the last sacral being 5 lines, while that of the
first sacral is 2 inches 2 lines.
The ilium is divided, as usual, into two parts by the ridge on its
upper or outer surface (ib. fig. 2, _r_), extending obliquely backward
to behind the acetabulum—the anterior division being narrower and
concave, the posterior broader and convex but in a minor degree. The
anterior (slightly thickened) border of the ilium is curved with the
convexity forward, extending 8 or 9 lines in advance of the fore
part of the neural spine of the first sacral vertebra. The ilia
almost meet above that of the second and third sacrals, with which
they coalesce, and then diverge to the oblique boundary ridge, which
is thence continued, in some with an angular bend, more directly
outward. At this angle the bone is so confluent with the sacrum that
the orifices leading to the ileoneural canals[26] are almost or quite
obliterated. These canals are, here (ib. _i ï_), the longitudinally
extended cavities intercepted between the fore parts of the ilia and
the continuous coalesced sacral spines and diapophyses, widening to
their anterior outlets. The extent of that part of the ilium in advance
of the acetabulum is 3 inches 8 lines; the breadth at its middle part
is 2 inches. As the ilium approaches the acetabulum it increases in
thickness, and is grooved at the outer margin by a vessel which leaves
impressions of its ramifications upon the upper concave surface of
the bone (ib. fig. 2, +62+). The acetabulum (ib. _a a_) is circular,
11 lines in the diameter of its outlet, 9 or 10 lines in that of its
inner circumference, being widely open, as usual in birds, towards the
cavity of the pelvis; the trochanterian surface (ib. _t t_) above the
acetabulum is elliptic, with the long axis lengthwise, 9 lines by 6 in
its diameter, with its upper border sharp and produced; the anterior
border (ib. _b_) of the acetabulum is slightly produced; the position
of this articular cavity is about midway between the fore and hind ends
of the pelvis. The oblique external ridge of the ilium terminates in
the outer margin of the broader part of the bone (ib. _r′_), 7 lines
above the sharp and prominent margin of the trochanterian surface
(ib. _t_). The ilia have diverged from each other for the extent of an
inch and a half behind the beginning of the boundary line (ib. _r_),
which interval is occupied exteriorly by lateral ossification from
the neural spines to the diapophyses of that part of the sacrum: the
mesial borders of the ilia (ib. fig. 2, 62′) slightly converge to the
fifteenth sacral vertebra, where they are separated by an interspace
of 1 inch, and then again diverge to the last sacral; they coalesce
with the diapophyses (ib. fig. 2, _d_ _d_). The inner or under surface
of the ilium is thickened into a kind of buttress (ib. fig. 1, _e_),
terminating behind the ischiadic foramen. The breadth of the iliac
bones and intervening sacrals, 1 inch behind the acetabulum, is 5
inches; at the back part of the pelvis it is 4 inches. The outer border
of the posterior part of the ilium (ib. fig. 2, _g_) projects as an
obtuse ridge above the ischiadic foramen and the succeeding expanded
and confluent part of the ischium (ib. 63), which is vertically
concave externally: the ilium, ischium, and pubis (ib. fig. 1, 64)
have completely coalesced around the acetabulum. The pubis, which in
this part is 7 lines thick, contracts as it becomes free to a diameter
of 4 lines; it is smooth and convex below, and has been broken off
near the acetabulum on both sides; the fracture shows its pneumatic
structure. The ischium, as it recedes from the acetabulum, contracts
to a trihedral column, with a vertical diameter of 4 lines; it is
concave outwardly, convex inwardly, and suddenly expands below, about
an inch from the acetabulum, to form part of the posterior boundary of
the obturator foramen (ib. fig. 1, _f_), which is 9 lines in length,
and is situated one half in advance of, and the other half beneath,
the ischiadic foramen (ib. _m_). This latter is oval, with the large
end forwards, 1 inch 3 lines by 10 lines in its principal diameters.
Behind this foramen the ischium is confluent with the ilium for an
extent of 2 inches, or perhaps rather more, as the posterior margin of
the pelvis is not entire in any of my specimens. The inner surface of
the ischium forms a low, obtuse longitudinal ridge towards the pelvic
cavity, losing thickness as it recedes from the acetabulum. The chief
pneumatic foramina in the pelvis are on the inner surface, above the
acetabulum, behind the trochanterian articulation, and behind the iliac
confluence of the last sacral pleurapophyses,—also at the hinder part
of the ilium, on each side of the transverse buttress (ib. _e_) near
its posterior junction with the ischium. The prærenal fossa (between
_pl_ 4 & _pl_ 8, fig. 1) is deep and subdivided by the diapophysial
plates: the postrenal fossa is wide and shallow.
_Sternum._ (Plates III., IV., VI., XI.)
Of this instructive and determinative bone there are two specimens, the
one most entire (Pls. III., IV. fig. 4, & VI.) measuring in a straight
line, from the costal process to the hind border, 7 inches. The extreme
breadth between the lateral processes (Pl. IV. _h_) is 4½ inches; from
this diameter the bone contracts anteriorly to a breadth of 3½ inches
at the costal processes (ib. _d_), and posteriorly it contracts more
rapidly to an obtuse, horizontally flattened apex (Pl. VI. fig. 3).
The anterior border of the sternum (Pl. IV. fig. 4) is widely and
rather deeply emarginate at the middle (_e_), less deeply so on each
side: the breadth of the mid notch (_b_ _e_ _b_) is 1 inch 9 lines,
that of each side notch (_b_ _d_) is 1 inch 2 lines. The sternum is
deeply hollowed above (Pl. XI. fig. 4), correspondingly convex beneath
(ib.); the keel (_s_) is low and thick, commencing by a pair of broad
obtuse ridges (Pls. IV. fig. 4, & VI. fig. 1, _r_ _r_) from the mesial
ends of the outer walls of the coracoid grooves (ib. _b′_), which
gradually rise from the surface of the bone as they extend backward,
converging to form the beginning of the keel about 2 inches from the
anterior emargination (_e_): the keel gains a depth of ¾ of an inch at
the middle of the sternum, then gradually sinks to the level of the
bone, as it extends backward, at 1½ inch from the hind end (Pl. VI.
fig. 3), a little increasing in thickness as it subsides: its free
border describes a pretty regular convex curve (Pl. III.); it is thick,
flat, partially canaliculate: the sides of the base of the keel expand,
to be continued gradually into the body of the sternum (Pl. XI. fig.
4). Behind the costal surface (Pl. VI. _c_), on each side, extends a
lamelliform process (Pls. III. & VI. _h_), ½ an inch in breadth, upward
and a little outward, slightly expanding to its free termination,
which, however, is not entire in either specimen: the longitudinal
extent of this characteristic process, where it is best preserved, is
1 inch; it is conjecturally restored in Plate III.; it answers to the
ectolateral process (_h_) of the gallinaceous sternum (Pls. III. & XII.
fig. 3): there is no trace of an entolateral process (ib. _i_). The
thin margin of the Dodo’s breast-bone, behind the ectolateral process
(Pls. III. & VI. _h_), is entire and uninterrupted to the obtuse apex,
and the body of the sternum is imperforate: the notch (_f_) behind the
process (_h_) represents the ectolateral notch of the gallinaceous
sternum (Pl. XII. figs. 1 & 3, _f_). The costal border (Pl. VI. fig.
2, _c_) is 1 inch 9 lines in extent, and 6 lines across its broadest
part; it shows articular surfaces for five sternal ribs, of which the
four posterior (2–5) are bilobed, the anterior one (_c_ 1) simple,
and limited to the outer half of the border; the second sternum shows
some variety in this respect: the deep interspaces, in both, are
perforated by pneumatic foramina. The costal process (_d_)[27] in
advance of these surfaces expands, as it rises upward and a little
outward and forward, to the extent of nearly an inch; the hinder and
outer side is impressed by a concavity, continued from the costal
border; the inner side is smooth and convex: it is not quite entire on
either side. The coracoid grooves (Pl. IV. fig. 4, _b_ _b′_) are small
in proportion to the sternum, and are divided from each other by an
interspace of about an inch; the outer wall of the groove (_b′_), 9
lines in extent, is moderately produced and convex; it appears to be a
continuation of one of the initial ridges (_r_) of the keel: the inner
wall of the groove (_b_) is deeper, and is formed by the obtuse angle
of the anterior border of the sternum, between the medial and lateral
emarginations. External to each coracoid groove is a large elliptical
pneumatic foramen (_p_) or depression. There is no episternal process.
On the convex outer surface of the body of the sternum the “pectoral”
ridge (Pl. VI. fig, 1, _k_)[28] is feebly indicated, extending from
the outer end of the coracoid groove backward and inward to near the
posterior third of the keel. The concave surface of the sternum (ib.
fig. 2) shows a number of small pneumatic foramina, chiefly along the
middle line to near the posterior third. Behind the costal border the
substance of the sternum gradually increases in thickness from the
sharp lateral margins to the middle, above the base of the keel, and
shows there a fine pneumocancellous texture (Pl. XI. fig. 4).
_Scapular Arch._ (Plates III. & VIII.)
This consists of the scapula (Pl. VIII. figs. 6, 7, 8 & 9, 51),
coracoid (ib. figs. 4 & 5, 52), and clavicle (ib. 58), the latter
ending in a point and here tied by ligament to its fellow, to form
a furculum. I have received the elements of this arch in three
conditions:—one in which the bones, though of full size, are separate;
a second, in which the scapula and coracoid are confluent, but the
clavicle distinct; a third, in which the three bones are confluent
at the ends converging to the humeral articulation. The scapula (ib.
figs. 6, 7, 8 & 9, 51), 3 inches 7 or 8 lines in length, has the
usual sabre-shaped body, slightly expanding and decurved at its free
extremity, the breadth of which is 7 lines: it terminates obtusely:
varieties of shape are shown in figures 6 & 8. The outer surface of the
bone, at the two posterior thirds of its extent, is slightly concave
and marked by muscular attachments; the inner surface of that part is
smooth and slightly convex: the bone increases in breadth, with some
diminution of thickness, towards the articular end, and is remarkable
for sending off from the lower border, at 7 or 8 lines from that end,
a short process (ib. 51); between this process and the articulation
the breadth of the bone is little more than 3 lines; the breadth of
the articular end is 9 lines. Nearly one-half of it is occupied by the
almost flat, subcircular humeral surface (fig. 8, _a_), with a diameter
of 4½ lines, and directed upward, outward, and a little forward. From
this is continued an oblong, much narrower coracoidal surface, beyond
which the acromial process (fig. 6, _c_) extends forward, curving
toward the coracoid, and terminating obtusely.
The coracoid (ib. figs. 4, 5, 8 & 9, 52), averaging a length of 3
inches 7 lines, expands to a breadth of 1 inch 3 lines at its sternal
end (52), of which the articular surface (_e_) occupies an inch; the
non-articular part forms the outer angle (_m_), and extends in advance
of the pneumatic foramen (Pl. IV. fig. 4, _p_) at that part of the
breast-bone: the outer border which extends from this free angle to the
body of the bone, into which it subsides, at one-third of the extent
of the bone, is sharp; the inner border is obtuse to near the inner
angle (Pl. VIII. figs. 4 & 5, _n_). The outer surface of the expanded
sternal end is smooth and convex; the inner surface is flatter and
more irregular, perforated by pneumatic foramina; the diameter of the
subcylindrical part of the shaft is 4 lines: the extremes of difference
in the distal expansion of the coracoid are shown in figs. 4 & 8, 52,
Pl. VIII. A muscular ridge and rough surface (ib. fig. 9, _r_) mark
the back part below the middle of the shaft. The bone then expands
to its upper articular end, which is obliquely truncate from within
outward: it shows, first, the oblong surface for the scapula, which is
extended upon the inner prominence of that end; next, the larger and
full oval surface for the humerus (_h_), from which the thick, obtuse,
inner continuation of the scapular end projects inward, forward, with
a slightly upward curve, and shows the narrow oblong surface for the
articulation and ultimate confluence of the clavicle (58). The coracoid
unites with the scapula at an angle of 100°.
The clavicle (ib. figs. 4 & 5, 58), at its scapular end, is slightly
expanded, compressed, with an obtuse recurved termination articulating
with the above-named surface of the coracoid, and in one instance
coalescing therewith, and by extended ossification with the “acromion
scapulæ” (ib. figs. 8 & 9). As the clavicle descends it curves slightly
and contracts to a point. The angle at which the pair meet is shown in
figs. 4 & 5.
_Bones of the Wing._ (Pls. III. & VIII. figs. 12–17.)
Of the humerus the series contains two specimens, both measuring 4
inches 3 lines in length, one right, and the other left (Pl. VIII.
figs. 12–14), but differing slightly in their proportions and in
colour—one being of the olive-brown tint with which most of the bones
are stained, the other black. The articular head (ib. _a_) is an
elongate oval convexity, with the larger end toward the radial side,
prominent toward the back and rather flattened toward the front of the
bone, which there swells out beyond the base of the articular surface.
The radial tubercle is small, and descends from the radial end of the
head for about 5 lines; the pectoral process (ib. _b_) is triangular,
obtuse, short, and bent, or directed toward the front side of the bone:
the ulnar tuberosity (ib. _c_) is more produced in that direction; it
is oblong, obtuse, with its base impressed by a large pit both above
(fig. 12, _h_) and below—the lower one (ib. _g_) being the deepest,
and perforated by a pneumatic foramen; the convex, broad, ulnar border
of this tuberosity has two slightly produced processes, an upper or
posterior (ib. fig. 12, _c_) and a lower and internal (ib. _g_), which
is the smallest. The breadth of the proximal end of the humerus, across
the tuberosities, is 1 inch 5 lines, beyond them the bone contracts
to a smooth subcylindrical shaft, showing at the back part of the
proximal third a longitudinal ridge (fig. 12, _r_), half an inch in
length; it gradually expands at the distal third to a breadth of 10
lines, where the articulations offer the usual avian characteristics
of the elbow-joint. The head of the humerus is occupied by a fine
cancellous structure: into the large vacuity below this, crossed in
the section figured (Pl. XI. fig. 5) by a transverse slender bar of
bone, the small pneumatic foramina at the bottom of the wide and deep
fossa for the axillary air-cell open. The part of the hollow proximal
end giving off the pectoral and other processes for the attachment of
muscles is strengthened by similar abutments. The pneumatic cavity of
the main part of the shaft of the humerus is simple, with a compact
wall thicker than at the ends of the humerus, but not exceeding that
which is characteristic of the long air-bones in birds. The portion
of the distal end chiefly serving for muscular attachments and the
antibrachial articulation are also cancellous.
The _radius_ (Pls. III. & XII. fig. 15) is a straight and slender bone,
3 inches 1 line in length, and 2 lines in chief diameter of the shaft.
The proximal articular surface is subcircular, 3 lines in diameter,
moderately concave; the distal end expands to the same extent, but is
compressed, as usual.
The _ulna_ (Pls. III. & VIII. figs. 16 & 17) is 3 inches 1 line in
length, of the usual ornithic character, with a well-defined, narrow,
elliptic, rough muscular depression, 8 lines in length (fig. 16, _c_),
extending upon the shaft from below the anterior or palmar angle of
the proximal articular surface. This bone has no pneumatic foramen;
the orifice for the medullary artery is above the middle of the same
palmar surface, the canal inclining distad. The shaft of the bone is
nearly straight; the back or anconal surface, which is slightly convex,
shows feeble impressions of the attaching ligaments of the alar plumes,
which are represented in all the figures of the entire or living bird.
A second ulna is 3 inches 3 lines in length.
There was no carpal or pinion bone in the collection of remains
submitted to me: this part of the wing is conjecturally restored in
dotted outline in Plate XV.
_Bones of the Leg._ (Pls. III., IX., X. & XI.)