attached to the marginal apicular articulation of the distal carpal,
thence extending proximally, and terminating in an articular facet for
the third bone of the fore-arm, so as to overlap laterally both of the
other carpals. The bone is compressed, is three times as wide as thick,
and in outline sub-quadrate with a distal talon. On the inner side it
is flat, and on the outer side above the talon it is concave vertically
and convex transversely in such way that the side of the bone to which
the distal articulation is adjacent is thicker than the other side,
and sometimes bent at a sharp angle. The talon on the inner aspect of
the bone is flat and continuous with the quadrate side, but on the
outer aspect it is separated from the side by an elevated transverse
thickening, distally to which the bone is compressed, and rounded into
the adjacent parts. The talon extends over more than half of the distal
end of the bone, and constitutes with the remainder of the distal end,
the distal articulation, which is flat from front to back, and concave
from side to base. The proximal articulation is cupped and extends over
the whole proximal surface; it is at right angles with the sides of the
bone. Both the inner and outer sides exhibit small pneumatic foramina.
No. 8 differs from the other specimens in its sub-triangular lateral
outline, and general less complex modifications.
The Carpus of the Cambridge Ornithosaurians at first sight is not
easily compared with that of Birds; Birds having but one bone between
the radius and the metacarpus. But that one bone in the Ostrich, for
instance, is not unlike in form to the proximal carpal of Pterodactyle;
while the proximal end of the metacarpus presents so close an analogy
with the distal carpal of the Pterodactyle, that even were it not
easily demonstrated that the bone in Birds commonly called the
metacarpus is a carpo-metacarpus[R], it would be strong evidence for
such a determination. In Birds there is a small lateral bone between
the ulna and carpo-metacarpus which is evidently homologous with the
lateral carpal of our Pterodactyles, and so, since this lateral carpal
of the Ostrich is the pisiform bone, it results that the lateral
carpal of Pterodactyle is the pisiform bone also. From this follows a
conclusion of the first importance in the interpretation of the hand.
The fine hair-like metacarpals of the Pterodactyle are on the side
towards the pisiform bone, while the great wing-metacarpal is on the
side towards the index finger.
[Footnote R: They separate without difficulty in the Chicken.]
In Birds the rudimentary thumb (or second finger, according to Owen)
has no connection with the carpus. In the Penguin, _Aptenodytes
Patagonica_, it has disappeared altogether, and there then remain two
fingers of which the outer one (seen from the front as we have placed
our animal) is the larger, and has the greatest number of phalanges,
precisely as in Ornithosaurians. Moreover the wing-metacarpal, in the
Penguin especially, is seen to unite with the carpus directly under the
radius, as is the case with the Cambridge Ornithosaurians. Hence it
follows that in Pterodactyles the thumb is not developed, and that the
wing-finger is not the little finger, but the index finger, precisely
as in Birds. If Goldfuss gave a reverse arrangement it was because the
hand in his specimen, as is proved by the claws, was upside down. In
the immature state the distal carpal of Pterodactyle appears to have
been composite.
Notwithstanding the opinions of eminent German philosophers to
the contrary no reptile has a carpus comparable to that of the
Pterodactyle. If some of them have two rows of bones and a pisiform
bone, so have mammals, and the mammalian arrangement is not more like
the Ornithosauria than is that in Reptiles.
METACARPAL BONE.
Pl. 6.
Case. Comp. Tablet. Specimen.
=J= _b_ 5 1-3
The illustrations of this bone comprise 31 specimens. Nos. 1 to 15
are examples of the proximal end, and Nos. 16 to 31 show the distal
trochlear end of the bone. No. 1, which is nearly entire, gives the
form and proportions of the wing-metacarpal in one species, but a
knowledge of its variableness in German forms would guard against an
assumption that all the other Greensand species were to be restored
on the plan of this example. It is 3-5/8 inches long, to which
three-eighths of an inch may be added for the distal articulation,
making the length up to 4 inches. The proximal end is not well
preserved, but in its wide measurement is 5/8ths of an inch; the distal
end in the same measurement is about 3/8ths of an inch. A large example
from the Chalk, in the Museum of C. Moore Esq. of Bath, shows the bone
more attenuated distally. No. 1 is compressed so as to be oblong in
section at the proximal end, and ovate in the middle of the shaft,
which is slightly smaller than the distal end. One of the lateral
outlines is straight; the other is concave. The bone is straight. In
No. 30 the shaft where thickest measures less than 1/4 of an inch,
becoming nearly circular in section. The shaft of No. 31 measures
nearly an inch in width at its distal end, rather more than half an
inch in thickness. No. 10 is 1-1/2 inch wide at the proximal end and
7/8ths of an inch thick. No. 9 would not have measured less when
perfect than 2-1/2 inches over the proximal end, so that if it had the
proportions of No. 1 it would have measured when entire not less than
16 inches in length.
The Proximal End.
The proximal end has never been figured. Prof. Owen's figure pl. IV.
fig, 4-5, First Supt. Cret. Rep. is probably part of a jaw, and not
the wing-metacarpal. The articular surface is oblong with one corner
rounded off so that the adjacent long and short sides become confluent
on the exterior surface of the bone.
In the middle of the flat inside margin and extending proximally is
a semi-cylindrical process, which is prolonged a short distance down
the side of the bone as an elevated ridge. On the flattened articular
end this process is bordered by a semicircular furrow which extends
half-way across the bone, outside of which is a slightly convex
semicircular band which extends to the outer margin of the bone,
except towards the short side opposite to that one which rounds into
the outer side, where there appears to be a narrow unarticular area.
On the inside of the bone where the two ends of the semicircular
proximal furrow terminate are two deep grooves which extend a short
distance distally; they are both limited by inward extensions of the
short sides of the bone, that crest being most developed in height and
length which is toward the flattened short side. The outline which
these modifications give to the inner side of the proximal surface
is intermediate in form between the letters S and [sideways M].
The Distal End.
The distal end has been figured by Prof. Owen in the British Fossil
Mammals, p. 545; in Dixon's Geology of Sussex, Pl. XXIX. fig. 12; Cret.
Reptiles, Pl. XXXII. figs. 4 and 5, First Supt. Pl. IV, fig. 9-11, and
other places, and fully described. It closely resembles the distal end
of a bird's tibia; and consists of a pulley-shaped end set obliquely
on to the compressed shaft, which just above the junction is reniform
in section, owing to the development of _a median rounded ridge_ on
the same inner side of the bone which bears the median ridge at the
proximal end, while on the opposite side there is a corresponding
_median depression_ which does not extend far proximally. In this
depression is an oval pneumatic foramen; on the right of the median
ridge of the other side, but placed more distally, is another pneumatic
foramen. The median ridge has sometimes a slight furrow on each side.
It terminates proximally in strong muscular insertions, which extend
round the right side of the bone; and distally, becoming more elevated
and rounded, it curves obliquely to the rights and forming one of the
sides of the pulley, passes round the base as three quarters of a
spiral, the termination extending laterally beyond the shaft. On this
side of the bone, distal to the median depression, arises another ridge
strong and well rounded, which is directed to the right, similarly
passes round the base as a spiral, and forms the other side of the
pulley. It is not so prominent as the border previously described.
While the spirals approximate at their origin, they become widely
separated at the base, making the articulation wider than the shaft. In
No. 31 the three inches of the shaft which remain show both pairs of
its sides sub-parallel; the widest measures nearly an inch; the base of
the articulation is less than a quarter of an inch wider.
Limited to the base, between the two outer ridges of the pulley, is
a short median ridge slightly developed; so as to flatten the middle
of the concavity between the ridges, and divide it into two grooves.
The degree to which the middle ridge is developed varies in different
species. In No. 30, the smallest pterodactyle, remarkable for a long
wing-metacarpal bone, it is not to be detected. The exterior sides of
the trochlear articulation are broad, flattened, and a little concave.
There is some variation in the way in which the shaft is set on the
trochlear end. It being often in the middle, but not unfrequently
inclined more to one side than to the other.
The metacarpus finds no close parallel among living animals. The
thread-like metacarpal bones suggest the condition of the hind-foot
in the Kangaroo. The predominant metacarpal suggests the ruminants.
But the nearest approximation is found among birds where the bone
for the middle finger is large and the bone for the third finger is
slender. This may be observed (among other examples) in the Penguin
and the Swan. But here the parallel ends. The proximal end in Birds,
we have already seen to be hidden by the anchylosed distal row of the
carpus, and the distal end though often convex from side to side never
presents the trochlear joint of the Pterodactyle. Consequently so far
as regards the form of the articular ends the resemblance is closer
with Reptiles and clawed Mammals than with Birds. In Birds the small
metacarpal is usually of similar length with the large one as is the
case with Pterodactyles.
FIRST PHALANGE.
Pl. 7.
Case. Comp. Tablet. Specimen.
=J= _b_ 6 1-10
No perfect specimen of the first phalange has been found in the
Cambridge Greensand. Ten bones are mounted to illustrate it, all of
them less perfect than others in the series of associated bones. No.
1 shows the heel of the proximal end; Nos. 9 and 10 are portions of
the proximal articulation from which the epiphysis which forms the
articular heel-part seen in No. 1 has come away. Nos. 2 to 8 are the
distal articular ends of first phalanges. It is improbable that any of
them belong to the second phalange, since they agree in form, and show
muscular attachments which correspond.
Prof. Owen has figured the shaft of a fine example of this bone in
Dixon's Geology of Sussex, Pl. XXXIX. fig. 11. A good proximal end is
shown in Pl. XXXII. fig. 2, of Prof. Owen's monograph of the Cretaceous
Reptilia, but the figure appears to have been previously given in Pl.
XXIV. fig. 2 of the same monograph. By far the grandest specimens are
drawn in Pl. XXX. Prof. Owen names these wing bones. In the "Literature
of English Pterodactyles" the loss of the proximal epiphysis from the
specimen represented in Prof Owen's fig. 1 and 2 led me to interpret
the bone as an ulna. Figs. 1 to 4 represent the proximal ends and
greater portions of the shafts of first phalanges. The lower bone
in fig. 5 is neither radius nor ulna, as stated in the text of the
Cretaceous Reptilia, but the shaft and distal end of a first phalange;
the upper bone being the second phalange.
The Proximal End.
The straight shaft throughout its length is triangular in section. One
side of the bone is gently convex; this may be named for convenience
the outside. The two parts which make up the other side are inclined,
and have the angle in which they meet rounded; one part looks upward
and inward, the other downward and inward. Towards the proximal end the
bone widens and thickens, and the moiety of the inner side which is
away from the heel becomes cleft, and has the sides of the depression
rounded to form a large pneumatic foramen. The articular surface looks
upward and a little outward on the side of the pneumatic foramen.
It consists of two semicircular concave grooves, separated by an
intervening low convexity. The outer of these grooves extends from the
margin of the extreme proximal point of the heel to the widest point
of the bone; the other groove more deeply concave, is a third shorter,
extending from inside the pneumatic foramen to the heel. Here both
grooves converge, terminating in a point, exterior to which a little
distally is a hemispherical mammilate eminence. On the distal side of
the eminence there is a depression so as to make the angle behind the
heel almost hemispherically rounded. This articulation fits on to the
distal articulation of the wing-metacarpal.
When the proximal epiphysis forming the heel comes away, it leaves a
large sub-circular pit with a depressed narrow border.
Distal End.
On nearing the distal end, the angle of the inner side of the shaft
becomes more depressed; and the articulation becomes an elongated oval,
slightly convex transversely and convex in length so as to extend
distally in a curve in such way that the articulation looks downward
and outward from an aspect of the bone exactly opposite to the aspect
from which the proximal articulation looks upward and inward. Hence
the two articular surfaces are sub-parallel; but the distal one at
its distal termination is bent inward, so as to make the adjacent
lateral outline of the bone concave on the inside at its termination.
The articulation does not cover the most proximal part of the distal
surface.
SECOND PHALANGE.
Pl. 7.
Case. Comp. Tablet. Specimen.
=J= _b_ 7 1-14
On this tablet are mounted 14 specimens. Nos. 1 to 9 are examples of
the proximal end of the second phalange. If there were more than two
phalanges, of which there is no osteological evidence, it is possible
that proximal ends of succeeding phalanges may be included with these.
They all however resemble each, other so closely as to lend no support
to such a supposition. Nos. ?10 to ?14 have been mounted with the
proximal ends because they appear to be portions of the middle of the
shaft of the second phalange; they indicate a rapid distal attenuation,
favouring the idea of there being but two phalanges.
The proximal end of the shaft has the outer side flattened, rarely
concave, commonly slightly convex; the inner side being much more
inflated, and not dissimilar in form to the inner side of the first
phalange. Proximally the bone widens and one lateral outline extends
outward in a curve, on the inner side of which, under the proximal
articulation, is placed the pneumatic foramen. The elongated oval
articular surface is concave from side to side and concave in length;
it does not extend in length so far as the straight side outline,
exterior to it being a crescentic flattened or convex area. The distal
end attenuates more rapidly in some specimens than others, and appears
in Nos. 11, 12, and 14 eventually to become cylindrical; but none of
the specimens show its distal termination.
The phalanges of the wing-finger attain a grand development in length
which is not paralleled in Birds, nor surpassed in Bats. In the Ostrich
there are three phalanges in the wing-finger, while in Ornithopterus
there are two joints, and in other German Pterodactyles four joints.
The terminal joint in the Ostrich is a claw, but in Pterodactyle the
terminal joint appears to be unarmed as in ordinary birds. The form of
the bones in being compressed from side to side is more bird-like than
bat-like. But the claws in their compression from side to side are more
like the bat than the bird.
DISTAL END OF METACARPAL
or Metatarsal Bones.
Pl. 6.
Case. Comp. Tablet. Specimen.
=J= _b_ 7 1-14
Sub-cylindrical bones, apparently elongated, and a little compressed
obliquely, terminating distally in a slightly expanded trochlear
articulation. Some of them show on one side marks of an osseous
adhesion: this has led to their being regarded as claw metacarpals
rather than as the distal ends of tibiæ. But on the supposition of
their being claw metacarpals, they are as compared with the same bones
in _Pt. Suevicus_, out of all proportion large, since wing-metacarpals
from the Cambridge Greensand would not as a rule have a diameter
more than twice that of these bones. The trochlear articulation is
smaller in proportion to the shaft than in the wing-metacarpal, and
usually shows a pit at the side and grooves above for ligaments; the
mesial pulley groove is shallow and broad. Seven specimens are mounted
in illustration, of which No. 3 may be regarded as doubtful. It is
possible that they may be metatarsals.
CLAW PHALANGE.
Pl. 8.
Case. Comp. Tablet. Specimen.
=J= _b_ 8 1-3
These three sub-triangular bones, which supported the claws, are much
compressed from side to side, and consequently deep. The superior
outline is convex from front to back and rounded from side to side. The
inferior outline is concave from front to back, sometimes narrower,
sometimes broader than the upper part of the bone, while the inferior
aspect is always more flattened than the superior aspect. On each side
on the lower half of the bone is a deep groove. The articular end is
divided into an upper articular part, which extends as far down as the
lateral groove and a lower non-articular part with ligament markings.
The articulation is concave from above downward, and is divided into
two lateral parts by a mesial vertical ridge. The articular end is
about half as deep as the bone is long.
Pelvic Girdle and Hind Limb.
OS INNOMINATUM.
Pl. 8.
Case. Comp. Tablet. Specimen.
=J= _b_ 10 1-9
Nine specimens are mounted in illustration of the pelvic girdle: Nos.
1, 3, 4, 5 and 6 show the acetabular or femoral aspects. The right os
innominatum is exemplified by Nos. 1, 4 and 5; the left by Nos. 3 and
6. No. 2 shows the sacral aspect of a left ischium, and its attachments
with the pubis and ilium. No. 8 is the sacral aspect of a left os
pubis. No. 9 is the femoral aspect of a right OS pubis. None of the
specimens are sufficiently complete to give the form of any of the
bones. The only known example of an entire or nearly entire pelvis at
all comparable in form, is seen in the original specimen of Dimorphodon
macronyx figured by Buckland, _Trans. Geol. Soc._ Ser. 2. vol. III. p.
217. In nearly all the fossils from the Cambridge Greensand the bones
of the pelvis are anchylosed together.
The ossa innominata have been determined as right and left on the
supposition that the pelvis of the Dimorphodon is in situ, and from the
general correspondence of the form of the constituent elements with
elements of the pelvis in the lower mammals, reptiles, and birds.
Each os innominatum shows a hemispherical acetabulum which is slightly
elongated in antero-posterior extent In the Dimorphodon the bone which
is superior to the cup, that is to say, which extends dorsally along
the sacral vertebræ is prolonged anteriorly as a strong narrow straight
style, the base of which is seen in the parts marked _Ilium_ in Nos.
1 and 6. A more perfect example may be studied in a pelvis from the
Cambridge Greensand preserved in the collection of the Geological
survey. Posterior to the acetabulum a similar but stronger bony style
extends for more than the length of the acetabulum, curving slightly
downward at its posterior part. The dorsal outline of this portion of
the bone is slightly concave. The posterior horn like the anterior
horn forms part of the ilium which constitutes the upper half of the
acetabular cup. The os innominatum contracts in antero-posterior
extent below the acetabulum, and immediately widens again in a thin
concave bony expansion. The anterior or pubic outline is comparatively
straight, and at right angles with the ilium; the posterior or ischiac
outline is deeply cupped where the ischium unites with the ilium, and
becoming straight extends backward at a considerable angle. The ischium
contributes less to the pelvic cup than either the ilium or pubis;
it is flat in front and convex on the visceral side, rounding into
the narrow flattened posterior side. The pubis is separated from the
ischium by a suture extending vertically through the obturator foramen.
The obturator foramen [seen in No. 9] is small and oval, less than half
the diameter of the acetabulum, situated below its ventral border. It
passes obliquely downward and a little forward, and its opening makes
the exterior aspect of the pubis concave; the visceral aspect of the
pubis is convex from side to side like the ischium. The sacral aspect
of so much of the os innominatum as is seen, is concave from the dorsal
to the ventral margins, and is cupped behind and below the acetabulum,
the surface being rough. Among reptiles the ilium is chiefly behind
the acetabulum, in mammals it is chiefly in front. In the over-lapping
group, Aves, it extends both ways. Among the Amphibia the ilium is
chiefly anterior to the acetabulum. In Crocodiles it has a slight
extension both ways, in Dinosaurs the extensions are more marked and
the whole arrangement approximates to birds. But among animals which
have been affiliated with reptiles the Dicynodonts are the only order
in which there is a pelvis so mammalian and massive. If the ilium of
the Monotreme genus Echidna had a posterior extension, the pelvis would
be altogether comparable with the pelvis of this Pterodactyle, and
would differ chiefly in the larger obturator foramen, the perforated
acetabulum and the unanchylosed condition of the pelvic elements. The
pelvis of Apteryx does not make any near approximation.
Moreover specimens Nos. 3 and 4 show on the anterior pubic border,
about the base of the acetabulum, a slight pit or roughness to
which something has been attached, and in the original specimen of
Dimorphodon associated with the pelvis are two triangular bones which
recall something of the form of the prepubic bones of Echidna. Most
German Pterodactyles show on the OS pubis an enormous prepubic bone.
In Iguana the pubis forms at its anterior border, a sharp angular
process. In Chelydra the process is long and narrower, and arises
from the middle of the border. In Echidna this prepubic process has
become a distinct prepubic bone and is more elongated. Unlike the
marsupial bones it is attached to the pubis by a wide base. The
anterior pubic roughness of Cambridge specimens, and the loose bones
of the Dimorphodon, &c. indicate the existence of structures in the
Ornithosauria homologous with the prepubic bones of the Ornithodelphia.
So far as it is comparable with living animals, the ilium is altogether
avian, differing in being narrower; and the pubis and ischium are
mammalian.
The upper anterior corner is the most elevated part of the acetabular
border, as in the great Auk and some birds of vertical position of
body, and many mammals.
FEMUR.
Pl. 8.
Case. Comp. Tablet. Specimen.
=J= _b_ 11 1-16
Twenty-six specimens are mounted to illustrate the Femur. 10 are
proximal ends; 16 distal ends. But in the series illustrative of
species is an entire specimen of a right Femur 4 inches long. Fragments
Nos. 3 and 12 show proximal and distal ends twice as large, but most of
the examples are about the size of the entire femur.
It is a straight sub-cylindrical bone, flattened in front, a little
compressed from front to back distally, and (in one type) compressed
proximally from side to side behind. The distal articulation has a
broad shallow channel passing down from the front and imperfectly
separating two condyloid parts, which extend a little backward and
are divided behind. The outer condyle extends a little outward, and
so gives the outer side of the bone at the distal end an oblique
compressed aspect like that which prevails among birds and many
mammals. Proximally the shaft contracts suddenly and is produced
upward, forward, and inward as a rounded neck, as long as in the femur
of any mammalian carnivore, which expands rapidly at the end to form
the hemispherical ball, which articulates with the pelvic acetabulum.
No. 1 shows a well-marked pit for the ligamentum teres at the back part
of the ball. At the proximal end of the shaft below the neck is a large
pit for the obturator muscle, and at the outer front angle a great
trochanter. Proximally the bone can only be compared with the mammalian
Carnivora, Quadrumana and Man; distally it is avian and mammalian.
In one genus exemplified by specimens 5-10 the obturator pit is not
developed.
Sometimes the shaft is curved a little convexly, outward and forward.
TIBIA.
Pl. 8.
Case. Comp. Tablet. Specimen.
=J= _b_ 12 1-11