



1891.] Geology and Paleontology. 1125 
the Pterodactyls. The ilium has a long: anterior projection, with an 
expansion at or near the front end. Posteriorly it extends more 
stoutly upward and backward from the acetabulum, to form a close 
union with the three posterior sacral vertebra, terminating in a stout, 
styliform tuberosity on either side of the base of the tail. The pubis 
and ischium are thoroughly coéssified throughout (there may be a slit- 
like indication of an obturator foramen below), forming a broad, 
anteroposterior plate, which is narrowed to form a symphysis of about 
one inch in length, in the medium-sized species. Projecting down- 
wards and forwards, about midway between the acetabulum and sym- 
physis, there is a moderately thickened, angular projection, evidently 
tipped with cartilage in life. It corresponds to the pectineal process, 
and may have been_for the attachment of pectineal or rectus muscles, 
or for the so-called prepupic bone, a bone I have never seen in the 
hundreds of specimens which I have examined. A little below the 
acetabulum, and a little before the middle of the conjoined plate, there 
is a moderate sized, oval, anteroposterior, pubic foramen. On the 
border of the ischium behind, a little above the symphysis, is another 
tuberosity, larger and stouter than the pubic one. Between this 
tuberosity and the iliac tuberosity directly above, there is a large, deep 
sciatic notch. These two tuberosities seem to indicate that the animal 
in life was in the habit of resting upon these parts, a supposition fur- 
ther helped by the weakness of the legs and by the structure of the 
femur. There are indications of seven: sacral vertebrae in the speci- 
men described. Marsh has given five as the number in one species. 
With the specimen were two apparantly basal caudal vertebre of small 
size. The femur is a moderately stout bone, considerably shorter than 
the tibia, considerably curved, with a slender neck, set at only a slight 
angle with the shaft, nearly spherical head, and small trochanter,—all 
of which, together with the rather shallow imperforate acetabulum, 
would indicate great freedom of movement in the legs. The tibia is 
a slender bone, without marked cranial crest, and with a well-developed 
trochlear surface below. I know of no indications of a separate fibula. 
The foot is elongate and slender, the metatarsals articulating closely 
together above, the claws much smaller than those of the manus, and 
only slightly curved. There are three tarsal bones, two of them cuboid 
or angular, the third larger, and with a downward directed, pointed, 
hook-like process. It evidently indicates a rudimentary digit. There 
are four functional toes, the four elongate metatarsals in length indicated 
by the numbers 2, 1, 3, 4, of which the second is the largest. The 
phalanges may be represented by the formula I-2, II-3, III-4, IV-5 ; 



