746 The American Naturalist. [ August, 
articulating directly with the basihyal and not through the interposition 
of a long cartilage. The first four cervicals are very curiously inter- 
locked; the atlas gives off a process from its ventral surface which 
curves back to almost touch the axis; the spinous process of the axis 
overlies the atlas in front, and extends backwards until it nearly touches 
the spinous process of the fourth cervical, that of the third cervical 
being abortive. The fourth cervical sends down a long parapophysis. 
The dorsal vertebræ are apparently fourteen in number, and none ap- 
pear to have been lost. The last three ribs have no tubercle and unite 
with the middle of the centrum by a large head; the 10th and 11th 
ribs have a small tubercle although articulating with the body of the 
vertebra; the fifth rib is remarkable for its great upward curvature ; the 
second to seventh ribs are much swollen towards the distal extremities. 
The scapula is thoroughly cetacean in shape, as well as in the length 
of the acromial and coracoidal processes. The humerus is, as figured 
by Miiller, heavy at its proximal end and tapering rapidly towards the 
distal extremity ; the radius and ulna are so articulated with one an- 
other and with the humerus, as to permit flexion and extension only ; 
the olecranal process is large, wide and flat; the distal ends of radius 
and ulna are rough and their epiphyses may have been entirely carti- 
laginous ; two or three small bones of irregular form are very likely 
carpals, and if so they too were largely cartilaginous. No traces of 
hind limbs have as yet come to light. | 
The regular articular posterior extremity of the first sternal segment 
has led Professor Cope to suggest that the animal was in the habit of 
rearing the front part of its body out of water, and this suggestion 
derives additional weight from the shape of the articular faces of the 
dorsals; they indicate that not only was there movement in the dorsal 
region from side to side, but up and down, and show that the inter- 
vertebral cartilages were very thick. Many of the lumbo-caudals have 
the faces slightly approximated dorsally, indicating considerable vertical 
movement in this region. The change from the short centra of the 
dorsals to the extremely elongate centra of the lumbo-caudals is very 
abruptand the vertebral column doubtless terminated with equal abrupt- 
ness, since vertebr a long way from the head are very massive. A 
curious feature is the prominence of the anterior zygapophyses in the 
Jumbo-caudal region, since the spinous process are from 8 to 12 inches 
apart. Above all one is struck with the small size of the head and 
thorax when compared with the posterior region of the body, and it 
would seem that the head must have had a busy time in order to 
capture sufficient food to sustain the huge tail.—F. A. Lucas. 
