mammal. Most mammals have the proximal head of the bone hemispherical,
and a pit at the distal end for the olecranon process of the ulna,
while there is usually little indication of a radial crest, and the
proximal and distal ends are in the same plane. In the Bat however the
bone is twisted a little so that the slight radial crest looks in the
same direction as the distal end, here also there is no pit for the
olecranon; but the bone is sigmoid and proportionally much longer than
in Pterodactyles. In the horse, hippopotamus, &c., the radial process
becomes more developed but never resembles that of a Pterodactyle.
Among reptiles, the bone may be compared with lizards and crocodiles.
In crocodiles the proximal and distal ends are nearly in the same
plane, the distal end has two condyles, the head is convex from side to
side, and the radial crest is moderately developed and never extends so
far outward or so far proximally as in Pterodactyle. In the Chameleon
the bone is more twisted than in Crocodile, and as in Pterodactyle
the distal end is compressed on the radial side to a sharp margin.
In Iguana, Scink, and Monitor both proximal and distal ends are much
expanded, and the radial process makes no approximation to that of a
Pterodactyle.
The bird humerus does not approximate more closely in form to that
of the Pterodactyle than does the Chameleon humerus, though it has
the cardinal distinction of pneumatic foramina, and these sometimes
corresponding in position in the two groups.
The bird humerus is commonly longer, though in the parrots the
proportions and straightness are not unlike Pterodactyle. In
some respects a nearer resemblance is seen in the raptorial bird
_Gypogeranus serpentarius_, in which the radial process is rather more
developed than in the Crocodile, and extends further proximally though
still much smaller than in Pterodactyle; here too the superior surface
is concave from side to side, and the distal articulation is not unlike
that of some Pterodactyles. But no Pterodactyle has the head of the
humerus convex from the radial to the ulnar sides, and the bird is
distinctive in having the ulnar crest developed on the inferior side
of the head: a faint approximation to a similar development is seen in
Crocodile, but there is no trace of such a process in Pterodactyle. The
distal end is more Bird-like than Lacertian in form, but is twisted to
a greater angle with the proximal end than in birds.
Altogether the bone is distinctive. The points in which it is unlike
birds and reptiles are those in which Birds and Lizards resemble each
other; it would not be easy to say that in form it resembles one group
more than the other. But it is linked with birds by the pneumatic
foramina.
RADIUS AND ULNA.
Case. Comp. Tablet. Specimen.
=J= _a_ 9 5- 6
10 1-10
11 1- 7
12 1- 4
13 5- 6
Of neither of these bones has a perfect specimen been found. While
fragments of humeri are met with frequently, fragments of these bones
are rare. In accordance with the analogy with birds the Ulna might
be presumed to be the larger bone of the two. But from a study of
German specimens the larger bone is found to be the Radius, which
according to the mammalian plan is placed in front of the ulna. As a
whole, the fore-arm of Ornithosaurians is only to be compared with the
insectivorous mammal _Chrysochloris Capensis_, in which there are also
three bones in the fore-arm,--the third bone like the _Pteroid bone_
in Ornithosaurians, extending about half-way from the carpus to the
humerus, and holding, relatively, a similar position and development to
the fibula in bats.
The pteroid bone articulated with a separate carpal, and was placed
on the side of the arm, adjacent to the radius, which at the distal
end extended in German specimens more inward than the ulna. In
Chrysochloris the third bone appears to be behind the other bones, and
adjacent to the ulna[P].
[Footnote P: See D'Alton and Pander _Chiropteren und Insectivoren_,
Bonn, 1831, pl. 5, Chrysochloris.]
Among neither birds nor reptiles is any comparable modification of
the fore-arm to be found. Then by examining the proximal surface of
the proximal carpal, the characters of the distal end of the Radius
are readily discovered. The proximal carpal shows on the same surface
another articular facets with which however only one fragmentary distal
end of a bone corresponds. That accordingly is identified as the ulna.
Besides these, three other articular ends of bones occur, one of which
fits on to the distal end of the femur. The remaining two are both
large bones, with epiphyses which formed portions of the articular
surfaces, and are usually wanting. One of these bones corresponds in
form with the ulna of a bird, and would fit the facet on the ulnar
side of the distal end of the Pterodactyle humerus. The other bone
is massive with a sub-quadrate articular end, and might well be the
proximal end of the radius. Some specimens are among the largest
fragments of Pterodactyle bone known. The only other bone that either
of these could be is the distal end of the tibia, a bone not yet known,
but probably not unlike that of a bird.
I. Distal End of Ulna.
Four specimens which show articular ends such as the ulna should have,
are mounted together. They are compressed bones with the section of
the fracture elongately oval; and the shaft widens from the fracture
to the articulation without increasing in thickness. The outer surface
is gently convex, becoming concave mesially near the articulation;
the inner surface has the same characters, only the concavity at the
extreme distal end reaches from side to side of the bone. The two short
sides both look outward as well as laterally; one of them flattened so
as to thicken the bone, is concave in vertical outline owing to the
extreme distal end turning suddenly outward; the other side a little
convex, compresses the bone and inflects its inner margin. The longest
specimen measures 1-5/8 inch; 5/8 inch wide at the fracture, and 1-1/8
inch wide at the distal end. The greatest thickness at the distal end
is half an inch, the thickness of the fractured shaft is 5/8 of an inch.
The articular surface appears to have an elongated sub-reniform shape,
the part at the compressed side of the bone being narrower than the
broad ovate part on the thick side of the bone, to the lateral limit
of which it extends, while the narrow part does not extend laterally
nearly so far as the inflected border, which appears to give attachment
to powerful muscles. There is also a strong muscular attachment at the
corresponding diagonal corner of the bone where the outer surface on
its right meets the side of the bone in an elevated ridge.
In its long diameter the articulation is a little convex; transversely
it is very convex in the ovate part, but more flattened in its narrower
continuation. Where widest it measures about 4/10ths of an inch.
Nos. 5 and 6 on another tablet appear to be distal ends of ulna of
another kind of Pterodactyle. They are less compressed, more quadrate
in section, and have the sides more nearly parallel The flattened
side similarly has a concave border, but instead of having its distal
termination developed laterally, has it thickened behind. The opposite
side of the bone which in the other specimens was compressed is here
thick and well rounded, and not at all inflected. There is an absence
of the concavity noticed on the outer surface of the bone in the
compressed specimens. The articular surface is much flatter, and a
little concave in length instead of being convex; as in the other
examples it looks downward. The largest fragment. No. 5, measures 1-3/8
inch long; it is 6/8 inch wide at the fracture, and 4/8 inch thick. The
sub-quadrate distal end is more than an inch long, more than 4/8ths
inch thick on the thick side, and nearly 4/8ths inch thick on the
compressed side.
II. Distal End of Radius.
The best preserved of the 10 specimens here exhibited is 3 inches long,
No. 2. The shaft is oval, flattened on one side; measuring at an inch
from the fractured end 7/10ths of an inch in the least diameter, and
one inch in the wide diameter. It widens distally at first slowly,
then rapidly, till at the articular end its greatest width is two
inches. But while expanding laterally it contracts from side to side,
the more convex side of the two at about an inch from the articular
end, beginning to approximate to the flatter side till the articular
end has a short diameter of less than half an inch.
On the left-hand corner of the convex inner side of the bone is an
elevated flattened disc for muscular attachments, fully half an inch
in diameter, there is a slight muscular attachment interior to this,
nearer the middle of the bone. The left-hand corner of the flattened
outer side of the distal end of the radius is marked by a vertical
ridge bordering a similarly elevated oval muscular attachment. Parallel
to this nearer the middle of the side is a much stronger and acutely
elevated ridge.
The articulation is made up of three distinct parts, all in a straight
line. The portion of bone adjacent to the large muscular disc is
compressed and rounded on the distal end; then first there is a rather
deep circular cup 3/8ths of an inch wide, nearer to the more convex
than to the flatter side of the bone; adjacent to this cup is a convex
ball of about the same size; while the remainder of the articulation
is concave in length, convex from side to side, and looks downward and
a little towards the inner convex side of the bone. The specimens are
arranged so as to display these characters.--The example described is
of nearly the same size as that figured for the humerus in fig. 1, T.
XXIV. of the Cretaceous Reptilia. The less well preserved bone in that
figure exhibits the Ulna in its true position behind the Radius.
III. Proximal End of Ulna.
This bone has much the proportions of the Ulna in birds, the smaller
specimens nearly resembling the ulna of the Heron. The specimen (No.
1) with the shaft best preserved is 2-1/4 inches long, cylindrical at
the fracture, where it measures in diameter 3/16ths of an inch. It
gradually enlarges proximally widening to about 7/10ths of an inch;
near the proximal end it is a little curved, the side which is concave
in length being a little flattened, while there is a lateral elevation
on the opposite side, apparently corresponding to the quill-ridge on
the convex side of the bird-ulna. There is a separate ossification for
the olecranon, which is an irregular sub-oblong bone forming the outer
part of the articulation; it is only preserved in No. 1. Nos. 4, 5 and
6 show the concave transverse groove from which it has come away.
The articular surface looks upward and forward, in which aspect it has
a trapezoidal form. Sometimes, as in No. 2, the great sigmoid area is
divided into two parts by a vertical ridge, the more elevated part
of the articulation on the radial side of the bone being concave,
while the outer part, as in the heron, besides being concave, has its
border on the concave side of the bone produced and rounded. There is
a small triangular elevation on the radial aspect of the proximal end
like that on the corresponding part of the ulna of the heron. On this
aspect the bone is flattened, on the opposite and outward aspect it is
compressed and produced as in the bird. No. 2 measures 1-1/8 inch over
the articular end. The series includes 6 specimens.
IV. Proximal End of Radius.
This bone terminated in an epiphysis which formed part of the articular
surface, and has disappeared from all the 7 specimens mounted. So much
of the articulation as remains does not oppose the idea of its having
been attached to the humerus, while the large size of the example No.
7, which could not have measured less than 2-1/2 inches from side to
side over the articulation, is more in accordance with what is at
present known of the dimensions attained by the distal end of the
humerus than with the size that would be expected in the distal end
of the tibia, which is the only other unknown bone to which these
specimens could be referred.
The longest specimen, No. 3, is 3 inches long; broadly ovate at the
fracture, measuring in the long diameter 1 inch, and in the short
diameter more than 3/4ths of an inch. Nearer the articular end the bone
becomes in section sub-quadrate or rather sub-rhomboid. No. 1 shows
these terminal characters extremely well. On the posterior aspect of
the specimen the surface is divided into two flattened slightly convex
parts by a median vertical well-rounded angular bend. In front the side
is similarly divided into two parts, both of them a little concave
proximally, by a sharp median vertical ridge, which does not reach to
the articulation by a varying distance, never so long as the bone is
wide. The ridge terminates in, and is pierced by, a vertical groove
apparently for a nutritive vessel. Where the anterior and posterior
aspects of the bone converge laterally the sides are well rounded.
Only a small part of the articular surface is preserved, looking upward
and a little forward; it terminates the wider of the halves of the
bone laterally and in front. The remainder of the articular surface,
from which the epiphysis has come away, may be divided principally in
the majority of specimens into a posterior flattened median rhomboid
space and an oblong cup-shaped anterior space divided from it by an
elevated ridge. The extreme lateral termination appears to have been a
ball-shaped convexity.
The great length of the fore-arm relatively to the humerus,
characteristic of German Ornithosaurians, from the fragmentary
condition of Cambridge specimens is not seen.
Although the fore-arm resembles Chrysochloris in _plan_ the
resemblance is not close in the details of form. In many Mammals it is
characteristic for the radius to be the principal bone of the fore-arm,
and among Ruminants in which this is especially the case the radius is
altogether in front and the ulna behind as is the position with Birds
and Crocodiles. And among mammals with claws, as in the Lion, Bear,
&c., and in the Chameleon, it is characteristic, for the radius also to
be on the inside of the limb at the distal end, as in Ornithosaurians.
In form, ridges, and muscular attachments (see pl. 3) the distal end of
the radius approximates closely to the Bear and the Lion, and may also
be compared with the Bats and Birds, though with Birds it is a small
bone. From the epiphysis of the proximal end apparently being wanting
it would be difficult to compare closely. But though not like any
particular mammal, it might have pertained to a mammal since it has the
large perforation for the nutritive vessel near to the proximal end as
in the Camel and many of the mammalia.
The ulna of the Pterodactyles is at the proximal end altogether
distinguished from mammals by the slight development of the olecranon,
nor can the distal end, especially in its relation to the carpus, be
paralleled.
Among birds and reptiles the ulna is the large bone, and here a
general resemblance in form to the ulna of Pterodactyles is seen at
the proximal end. It is not compressed from side to side as in the
Crocodile, Iguana, Monitor, &c., but from back to fronts in this
rather resembling Birds than the Chameleon. It however at the distal
end is more crocodilian.
The fore-arm in plan is mammalian. The Pteroid bone is mammalian, the
Radius is mammalian and avian; the Ulna is avian, and crocodilian in
form, but mammalian in proportion. The pneumatic foramen of the ulna is
peculiarly avian.
CARPUS.
Pl. 5.
Case. Comp. Tablet. Specimen.
=J= _b_ 1 1-13
2 1-18
3 1- 4
4 1- 8
The pterodactyle wrist is made up of three bones, arranged as a
proximal carpal, a distal carpal, and a lateral carpal. Two of them
are figured by Professor Owen, who regarded the distal carpal of
this description as the scapho-cuneiform; while A very imperfect
example of the proximal carpal is named the unciform: neither of these
determinations, the reverse of those which follow, were given as more
than probable guesses.
I. Proximal Carpal.
No. 10 shows the proximal surface well; portions of it are seen in
Nos. 4, 5, 6, 8, 9, 11, and 12. The distal surface is best exhibited
in No. 1; portions of it are shown in Nos. 2, 3, 5, 7, 8. No. 13 is an
impression taken from the proximal sur&ce of a distal carpal to show
its correspondence with distal surface of the proximal carpal. The
bone is proximally of an irregular oblong form, being five sided, and
much broader towards the inner end than towards the outer end. The two
ends are sub-parallel, and rather obliquely connected on one side by
a nearly straight border more than twice as long as the shorter end.
The other limits of the sub-parallel ends are connected by two concave
borders meeting in a well rounded convexity, which is near to the
broader inner end.
The proximal surface of the bone is flattened, and may be divided into
a sub-rhomboid space, adjacent to the shorter of the sub-parallel ends,
which is moderately concave in the long axis of the bone and slightly
convex transversely, and an oblong space adjacent to the longer of
the two ends. This is separated from the sub-rhomboid space, toward
the straight side of the bone, by an elevated ridge sub-parallel
with the ends. It is directed towards the convexity on the opposite
side, in which the long and short concave parts meet, but after half
crossing the bone it becomes forked in a U shape, and less elevated;
the smooth unarticular included space shows an oval pneumatic foramen,
which varies in size with the different species. The region between
this Y-shaped ridge and the longer of the two ends, is sub-reniform,
slightly concave in its long diameter, and deeply concave in the short
diameter, exactly corresponding in form with the articular surface
already described as the distal end of the ulna. Also parallel with
the long end of the bone are marks of an articular surface exactly
corresponding with those described as the distal end of the radius;
that is, at the convex angle of the angulated side is placed a
hemispherical boss,' interior to which is a hemispherical concavity,
and extending toward the straight side is the oblique smooth border
of the sub-rhomboid area described. There still remains a space to be
accounted for. This consists of a sub-quadrate area forming the corner
of the bone made by the concave side and the shorter outer end; it is
made up of an inner concave part separated from the radial articulation
by a ridge, and an outer convex part constituting the shorter end of
the bone.
This carpal is moderately compressed from the proximal to the distal
side, except towards the shorter end of the bone, being there prolonged
distally into a wedge-shaped process, showing at its termination marks
of a powerful muscular attachment.
The outer lateral surface is of variable antero-posterior extent.
The distal articular surface is placed entirely toward the narrow
end of the bone, leaving at the proximal end a large smooth rhomboid
unarticular area, of which every side is a little concave: it connects
obliquely the proximal with the distal articular surfaces. The distal
articular area is divided by a diagonal ridge into a long oblong area
of which the inner and outer sides are sub-parallel and the ends
rounded: it is slightly concave in length as well as transversely, and
is slightly twisted like the flukes of a screw. Adjacent to this region
laterally is the other and sub-triangular part of the articulation.
The broad end of the triangle is toward the broad end of the bone; it
is concave in length and flattened transversely. The two parts of the
articulation are inclined to each other at a large angle, both looking
downward and outward, but on opposite sides of the bone.
II. Distal Carpal.
The tablets of this bone comprise 22 specimens. Nos. 2, 3, 4, 5, 6,
8, 9, 10, 15, 16, 19 and 22 are so mounted as to exhibit the proximal
surface. Nos. 7, 11, 12, 13, 14, 15, 16, 20 and 21 show the distal
surface of the bone. No. 17 is a cast from the distal sur&ce of a
proximal carpal for comparison with the proximal surface of the distal
carpal. No. 16 is a cast from the proximal end of the wing-metacarpal
for comparison with the distal surface of the distal carpal. No. 20
is a distal carpal of unusual type, 19 is a cast from its proximal
surface, and 21 is a cast from the distal surface of the same specimen.
The proximal aspect of this bone is rather narrower than the distal
aspect; each is sub-triangular in outline, the sides being convexly
curved. In the long axis from the apex on the inside to the short
outer[Q] side the bone is convex proximally with an oblique transverse
depression; in the short axis, that is, between the two longer sides,
the middle of the bone is hollow, but the oblique transverse depression
makes both sides of the hollow convex,--so that excepting the smooth
unarticular triangular area adjacent to the apex, the sub-quadrate
articular surface is shaped somewhat like two cones put side by side
in such manner that the apex of each touches the base of the other:
the apex of that cone which should touch the short side or base of
the triangle formed by the bone, is truncated by a depression which
exhibits an oval pneumatic foramen. Towards the apex, on the same side
as the pneumatic foramen, the margin of the bone is rounded for a small
terminal oval articulation which looks outward and upward.
[Footnote Q: Outer and inner are here used in accordance with the usual
interpretation, and the better to compare with birds.]
The lateral aspects of the bone are at right angles to the proximal and
distal surfaces. They are smooth, a little concave in antero-posterior
extent, and convex in the opposite direction. That one on to which
the marginal articular surface impinges is except for that surface
sub-quadrate in outline; the opposite side has a slightly crescentic
form, the flattened outline being distal. They show several small
foramina.
The distal aspect of the bone is comparatively flat. The distal surface
consists of a smooth unarticular part adjacent to the apex, rather
smaller than the corresponding area on the proximal aspect of the bone.
Between this part and the sub-crescentic articular surface, which
occupies the remainder of the distal area, is a large circular pit,
furthest removed from the side of the bone which forms the sub-apical
marginal articulation. The pit on the apical side shows several small
foramina; on the outer side of the bone the roughened articular
surface extends down the pit side. The articulation is flattened from
side to side of the bone. Its outer margin is slightly prominent, and
the margin of the pit is slightly convex and prominent, so that the
intervening articular surface in the direction between these limits
is concave. It is commonly divided into two parts by a median band
limiting a depressed half, which is in a slightly different plane
from the other half of the articulation. Where the depressed part
terminates towards the marginal articulation, which does not extend
so far distally, there is between the two a small step-like roughened
articular portion.
The large crescentic articulation described gave attachment to the
wing-metacarpal bone; if there was a second metacarpal terminating
in a claw, it must have been attached to the small articulation last
referred to. In No. 20 the pit is extremely small, the impressed part
of the articulation is small and deeply sunk, while the apicular
articulation is widened and shortened so as to make the outline of the
bone quadrate.
III. Lateral Carpal.