SCIENTIFIC SUMMARY. 
211 
on this important question. The author, after giving a brief sketch of the 
Sauropsida, and referring especially to those points in which the Pterosau- 
rians approach and differ from birds, spoke of the fossil birds and land 
reptiles which he considered to link together more closely the Sauropsida 
as a class. The most remarkable recent discoveries of fossil birds are : — 
I. Archceopteryx mact'ura (Owen), a Mesozoic type, which has a peculiar 
reptilian-like tail, composed of twenty free and apparently unanchylosed 
cylindrical vertebrae, each supporting a pair of quill-feathers, the last fifteen 
vertebrae having no transverse processes, and tapering gradually to the end. 
—II. Ichthyornis dispar (Marsh), discovered by Professor 0. C. Marsh in 
1872 in the Upper Cretaceous beds of Kansas, U.S. It possessed well- 
developed teeth in both jaws. The teeth are set in distinct sockets, and 
are more or less inclined backwards. — III. Odontopteryx toliapica (Owen), 
an Eocene bird from the London Clay of Sheppey, the skull of which alone 
has been discovered, has very prominent denticulations of the alveolar 
margins of the jaws. 
The author then referred to the Dinosauria, some of which he considered 
to present points of structure tending towards the so-called wingless birds. 
I. Compsognathus longipes (A. Wagner), from the Oolite of Solenhofen, is 
about two feet in length, having a small head, with toothed jaws, supported 
on a long and slender neck. The iliac bones are prolonged in front of and 
behind the acetabulum ; the pubes are long and slender. The bones of the 
fore limbs are small, and were probably furnished with two clawed digits. 
The hind limb is very large, and disposed as in birds, the femur being 
shorter than the tibia. The proximal division of th e tarsus is anchylosed 
with the tibia, as in birds. — II. The huge carnivorous Megalosaurus , ranging 
from the Lias to the Wealden, had strong but not massive hind limbs, and 
short reduced fore limbs ; it moved with free steps, chiefly if not solely on 
its hind limbs, which is true also of the vegetable-feeding lizards of the 
Mesozoic rocks. 
The author next drew attention to the Frilled Lizard of Australia 
( Chlamydosaurus Kingii , Gray), which has its fore limbs very much smaller 
than the hind limbs, and has been observed not only to sit up occasionally, 
but to run habitually upon the ground on its hind legs, its fore paws not 
touching the earth, which upright carriage necessitates special modifications 
of the sacrum and pelvic bones. 
The Solenhofen Limestone, in which Pterosauria are frequent, and which 
has yielded the remains of Archceopteryx and of Compsoynaihus , has also 
furnished a slab bearing a bipedal track, resembling what might be pro- 
duced by Chlamydosaurus or Compsognathus. It shows a median track, 
formed by the tail in being drawn along the ground ; on each side of this 
the hind feet with outspread toes leave their mark, while the forefeet just 
touch the ground, leaving dot-like impressions nearer the median line. 
Hence the author thought that while some of the bipedal tracks which are 
met with from the Trias upwards may be the “ spoor” of Struthious birds, 
most of them are due to the bipedal progression of the Secondary Reptiles. 
[This abstract was unavoidably (i crushed out” in our last number.] 
Further Evidence of the Anatomy of Hypsilopliodon Foxii has been brought 
before the Geological Society (Dec.) by Mr. J. W. TIulke, F.R.S., in a recent 
