of the Anatomy of the Sea Otter. 395 
with a quantity of loose cellular substance; this in the erected 
state is filled with blood, and forms a large glans six inches in 
circumference, and four inches long ; its anterior extremity 
is concave, and the end of the bone is seen in the centre. 
The penis, when erect, is 11 inches long. The erectores 
muscles are very strong. 
The globe of the eye is extremely small, and the optic nerve 
is small in the same proportion. Its internal parts were not 
in a state to bear examination. 
The articulation of the lower jaw admits of no motion for- 
wards or laterally ; it is a simple hinge an inch long, and very 
narrow. The condyle of the jaw is so much inclosed in the 
socket as to be with difficulty disengaged. 
The ribs are 14 in number, nine true, and five spurious. 
EXPLANATION OF THE PLATES. 
Tab. VIII. A side view of the scull of the sea otter, in 
which the articulation between the scull and lower jaw is dif- 
ferent from that in other animals: the condyle of the jaw is 
almost completely confined in the cavity adapted for it in the 
basis of the scull, so as to prevent all lateral motion, and make 
the teeth, when the jaws are closed, always touch upon the same 
surfaces. 
Tab. IX. A view of the basis of the scull, and the lower 
jaw separated from each other, to show the number and ap- 
pearance of the teeth ; and the peculiar shape of the condyles 
of the lower jaw, and of the oblong cavities in the basis of the 
scull with which they are articulated. 
Tab. X. fig. 1. A view of the thoracic duct, which in this 
3E 2 
