872 
is the marked elevation of the sacral spines 
above the ilium and the uniquely extensive 
and powerful union betwen the sacrum and 
ilia. The sacral spines are not only the 
highest spines in the vertebral column, but, 
as in the birds, the sacro-iliac junction is 
the center of power and of motion, and is 
of the most rigid character. 
The completeness of the tail with its 
chevrons is of great moment ; 37 caudals is 
the number estimated; 29 is the number 
fully or partly preserved ; 26 chevrons are 
preserved. The length of the tail is esti- 
mated at 9 meters, or about 29 feet—this 
estimate is obtained by the addition of the 
actual lengths of the centra. 
The caudals thus steadily increase in 
length from the first to the 18th and 
then steadily diminish toward the ex- 
tremity. Totally dissimilar from the cau- 
dals of other reptiles, and even from those 
of other Dinosaurs, the caudals of Sauro- 
poda or Cetiosauria are distinguished by 
profound changes in different regions. In 
proportions the anterior caudals are short, 
relatively broad, and spreading with heavy 
rugosities, as the seat of the powerful mus- 
culature of the tail, sacrum and femur. 
The median caudals (of the type first de- 
scribed by Marsh) are long, narrow and con- 
tracted, as the seat of the propelling fin ; 
the posterior caudals are long, slender 
cylinders. There are no less than five types 
of chevrons. 
The ilium is finely preserved ; the superior 
crest is perfect, but the anterior border is 
flattened or crushed inwards instead of 
turning sharply out to allow space for the 
two posterior ribs which lie in behind it. 
The superior crest, is directed mainly up- 
wards, the rugose border of the crest is sur- 
mounted by five diapophysial rugosities, 
that is those springing from the first pre- 
sacral vertebra, and from the four sacrals. 
The function of the heavy pre-acetabular 
bar appears to have been to support the 
SCIENCE. 
[N. S. Von. X. No. 259. 
weight of the body when the anterior por- 
tion of the trunk was raised and the tail de- 
pressed. 
Of the shoulder girdle only the scapula is 
preserved. Singularly enough this is the 
right scapula, for most of the skeleton rep- 
resents the left side. The femur is a highly 
characteristic bone. It is distinguished by 
a prominent trochanter placed on the pos- 
terior border, near the middle of the shaft, 
which apparently corresponds with the 
fourth trochanter, tr*, of Dollo. This is for 
the insertion of the great femoro-caudal 
muscles of birds and Dinosaurs. This 
femur is much more slender than that of 
Brontosaurus and has rather the proportions 
of the Amphicelias altus femur described by 
Cope. 
The greatly extended and revised knowl- 
edge afforded by this specimen may now be 
summarized. 
Dorsals—The neural spines arise from 
the convergence of paired cervical spines. 
There are no nodal or broad-spined dorsals 
as in Brontoswurus. The rib articulations 
are greatly elevated in the posterior dorsals. 
The two posterior dorsals are placed behind 
the ilium and bear one free and one coal- 
esced or vestigial rib. Sacrals.—There are 
four sacrals, three of which exhibit a com- 
plete coalescence of the spines, the fourth 
being more free and like a caudal. The 
sacro-iliac union is by means of sacral ribs 
and diapophysial plates. Additions to the 
sacrum are made from the caudal series. 
Caudals—All the anterior caudals have 
broad diapophysial lamine. These plates 
were first observed by the writer in Bron- 
tosaurus or Camarasaurus. There are five 
distinct types of chevrons. One of these, 
belonging to the 18th or 19th caudal, is the 
type to which Marsh assigned the name 
Diplodocus. Iliwm.—The superior crest of 
the ilium is directed upwards, and the 
coalesced sacrals form the center of motion 
and the highest portion of the vertebral 
