THE STRUCTURE AND RELATIONSHIPS OF ANCODUS. 
473 
no contact with the second ; this, however, is uncertain. From the character of 
the sacrum it may be inferred that Ancodus did not possess a very long or stout tail. 
No caudal vertebrae are preserved in the collection. 
With the exception of the atlas, which is longer and less broadened transversely, 
all of the vertebrm which have been described are extremely like those of Oreodon. 
They are, of course, much larger than in that animal, but their construction is 
essentially similar, while their resemblance to the vertebrae of the pigs is but re- 
mote. 
III. THE RIBS AND STERNUM. 
The ribs are somewhat more modernized than those of Oreodon, which are 
remarkable for their slenderness, though the dilference is in some degree to be cor- 
related with the great difference of size in the two genera. In Ancodus the first 
rib is short and nearly straight, the thorax being very narrow in front. Behind 
this point the ribs rapidly lengthen and become more and more strongly arched out- 
ward ; from the 3d to the 11th they are very long and indicate a capacious thorax. 
The first eight ribs are I’ather slender proximally, but for the distal two-thirds of 
their length they are much broader and more flattened than in Oreodon, though less 
so than in Anoplotheriimi. The 9th is more slender, while the posterior ones become 
decidedly so. The tubercles are remarkably large and prominent up to the 11th. 
Of the sternum the three anterior segments are preserved. The first segment is 
not entirely like that of either the Suina or the Pecora. In the former it is “com- 
pressed and keeled, the articular facets for the first pair of ribs are close together 
on its upper surface; but the mesosternum is broad and flat, the first segment being 
compressed in front, broad posteriorly.” In the Pecora “the presternum is narrow, 
rounded in front, and bearing the first pair of sternal ribs close to its apex. The 
succeeding pieces gradually widen, the posterior segments of the mesosternum being 
square, flat, and rather massive; they are hollowed at the middle of their lateral 
borders ” (Flower, No. 2, pp. 96-97.) In Ancodus the shape of the presternum 
is most like that of the ruminants, but it is much narrower, more compressed and 
less expanded at the free end. The facets for the attachment of the sternal ribs 
are not clearly shown, but appear to have been near the apex. The mesosternum 
is quite like that of the Pecora, save that the lateral borders are not so deeply 
ernm’ginated. The sternum of Oreodon differs in no important respect from that of 
Ancodus. fobe-limb. 
The scapula resembles, with some differences, that of the European species which 
Kowalevskv has described: “The general aspect of this new specimen presented 
great similarity to the one figured from Hordwell [i. e., of Diplopus\, begmnm 
fr^rtlTneck the bone broadened rapidly to its upper and broken extremity, and 
aco uired tlie same remarkable breadth which is so eonspicnous a feature of the scapula 
Toilhm The spine of the scapula was also very oblique, nicUnmg outwards, as 
t toltpulafigLd in Plate XXXV. The fossa glenoidea had precisely the same 
