40 MAMMALIA. 
cochlea, which terminates by one canal in the vestibule, and 
by the other in the tympanum. 
Their cranium is subdivided into three portions; the ante- 
rior is formed by the two frontal and ethmoidal bones, the 
middle by the two ossa parietalia and the os ethmoides, and 
the posterior by the os occipitis. Between the ossa parietalia, 
the sphenoidalis and the os occipitis, are interposed the two 
temporal bones, part of which belong properly to the face. 
In the feetus, the occipital bone is divided into four parts: 
the sphenoidal into two halves, which are again subdivided 
into three pairs of lateral wings; the temporal into three, one 
of which serves to complete the cranium, the second to close 
the labyrinth of the ear, the third to form the parietes of the 
tympanum, &c. ‘These bony portions, still more numerous in 
the earliest period of the foetal existence, are united more or 
less promptly, according to the species, and the bones them- 
selves finally become consolidated in the adult. 
Their face consists of the two maxillary bones, between 
which pass the nostrils; the two intermaxillaries are situated 
before, and the two ossa palati behind them; between these 
descends the vomer, a bony process of the os ethmoides; at 
the entrance of the nasal canal are placed the ossa nasi; to its 
external parietes adhere the inferior turbinated bones, the 
superior ones which occupy its upper and posterior portion 
belonging to the os ethmoides. The jugal or cheek bone 
unites the maxillary to the temporal bone on each side, and 
frequently to the os frontis; 3; finally, the os unguis, and pars 
plana of the ethmoid bone occupy the internal angle of the 
orbit, and sometimes a part of the cheek. In the embryo 
state these bones also are much more subdivided. 
Their tongue is always fleshy, connected with a bone called 
the hyoides, which is composed of several pieces, and sus- 
pended from the cranium by ligaments. 
Their lungs, two in number, divided into lobes, and com- 
posed of an infinitude of cells, are always enclosed, without — 
any adhesion, in a cavity formed by the ribs and diaphragm 
and lined by the pleura; the organ of voice is always at the 
