166 FIELD COLUMBIAN MUSEUM. 
away. Ten feet farther along the bank the distal end of the femur 
appeared. So hard was the: concretionary matrix, in which the skele- 
ton was encased, that drills and dynamite were at once called into 
service in order to make the excavation necessary for its removal. 
When the pelvis was reached the face of the stripping was eighteen feet 
in height. From this point the series of caudal vertebre curved back- 
ward, and dipping rapidly with the strata, led almost directly into the 
hillside. ‘These conditions made it necessary to resort to tunneling. 
Accordingly a chamber twenty feet in length by eight feet in breadth 
was excavated before the search for displaced caudal vertebrz was 
abandoned. 
The specimen as a whole was lying upon its right side, and appar- 
ently the entire skeleton had been present when embedded. The 
cervical vertebrze and the fore legs had beer carried away by a pro- 
cess of erosion so slow that comparatively few fragments were found 
upon the surface. The vertebre from the~last cervical to the thir- 
teenth caudal were but slightly displaced from their normal positions. 
(See frontispiece.) The remaining ten caudal vertebre recovered 
were found more and more dissociated, until tunneling for them became 
unprofitable. Some of the chevrons were associated with the vertebre, 
but most of them were displaced. The ribs were found in close ap- 
position with their respective vertebra. The right ilium was in posi- 
tion and codssified with the sacrum; the femur was scarcely removed 
from the acetabulum. The pubes and ischia were slightly displaced; 
the left illum was fragmentary. 
This specimen has been prepared for exhibition with great care 
and patience, employing the energies of three skilled men for more, 
than eighteen months. The spines and transverse processes of many 
vertebra were more or less distorted by the compressure to which they — 
had been subjected in the matrix. So far as was practicable, these 
distortions have been readjusted. The inevitable missing fragments 
have been replaced by plaster and carefully colored to match the 
adjacent parts. All portions thus restored are marked out by a line, 
not so conspicuous as to mar the general appearance of the specimen, 
but distinct enough to be readily recognized when examined closely. 
For information concerning the type specimen of Brontosaurus, 
and for advice in the preparation of this paper, the writer is indebted 
to Dr. S. W. Williston of the Museum staff. 
SYNONYMY. 
The number of terms applied to the group of reptiles variously 
designated as Sauropoda, Cetiosauria, and Opisthoccelia has led to 
