264 CETACEA 
from nose to median notch between the flukes of the tail, 624 
inches ; from the nose to the anterior edge of the dorsal fin, 29 
inches ; height of dorsal fin, 44 inches ; length of base of dorsal fin, 
8 inches ; length of pectoral fin, 9} inches ; breadth of pectoral fin, 
34 inches; breadth of tail flukes, 13 inches. The under jaw 
projects about half an inch beyond the upper one. The aperture — 
of the mouth is tolerably wide, and is bounded by stiff immobile 
lips, and curves slightly upwards at the hinder end. The eye is 
small, and the external ear represented by a minute aperture in the 
skin, scarcely larger than would be made by the puncture of a pin, 
situated about 2 inches behind the eye. The pectoral fins are of 
Fic. 93.—The Common Porpoise (Phocena communis). 
moderate size, and slightly faleate. The upper parts are dark gray, 
or nearly black, according to the light in which they are viewed, 
and the state of moisture or otherwise of the skin; the under parts 
are pure white. The line of demarcation between these colours is 
not distinct (washes or splashes of gray encroaching upon the 
white on the sides), and varies somewhat in different individuals, 
Usually it passes from the throat (the anterior part of which, with 
the whole of the under jaw, is dark) above the origin of the 
pectoral fin, along the middle of the flank, and descends again to 
the middle line before reaching the tail. Both sides of the pectoral 
and caudal fins are black. 
The Porpoise is sociable and gregarious in its habits, being usu- 
ally seen in small herds, and frequenting coasts, bays, and estuaries 
rather than the open ocean. It is the commonest Cetacean in the 
seas around the British Isles, and not unfrequently ascends the 
