74 Mr. Home's Description of the Anatomy 
being only about an inch long, and situated at some distance 
from the sternum, between two portions of rib, forming a kind 
of joint at that part. There is no ensiform cartilage. 
On the upper end of the sternum is a bone an inch lohg, 
which at its upper part has two processes that answer the pur- 
pose of clavicles, and unite with the upper part of the scapulae, 
keeping them at a proper distance. The scapulae have a very 
unusual shape: the posterior part is more like the imperfect 
scapula in the bird ; and the flat part is situated witli one edge 
under the bone, immediately above the sternum. The other edge 
forms the glenoid cavity, for the articulation of the os humeri ; 
so that the fore legs have their connection with the trunk more 
forward than in other quadrupeds ; and the scapula itself is much 
more firmly confined to its situation. 
This bone above the sternum, with the anterior part of the 
two scapulae, forms a bony covering of some strength, under 
which pass the great blood-vessels of the neck, secured from 
compression. 
The appearance of the ribs, sternum, and other bones, is 
represented in Plate III. 
The heart is situated in the middle line of the chest, its apex 
pointing to the sternum, and is inclosed in a strong pericardium : 
it is made up of two auricles and two ventricles. The foramen 
ovale between the auricles was closed, nor was there any com- 
munication between the ventricles. The right auricle is very 
large, and has two ascending venae cavae; that to the left 
winding round the basis of the heart, and forming the subcla- 
vian and jugular vein of that side, after giving off' the vena 
azygos. This is similar to the kangaroo, beaver, otter, and many 
other animals. The aorta and other arteries are small. 
