MAMMALIA. 543 
perfectly adapted for its marine life. It is essentially 
gregarious, living in herds or “schools,” and haunts the 
pelagic water, #.e., at or near the surface of the open sea, 
though not usually found far from land. Along with the 
rest of the Ce¢acea, it was for long regarded as a fish till the 
researches of Cuvier revealed its true relationships. 
The diet of the porpoise is fish, the pelagic species, 
such as mackerel, herrings and pilchards, being the usual 
victims. 
Fig. 374. THE CoMMON PorpolsE (Phocena communis). 
(From Flower and Lyppexer.) 
Passing to the internal characters we note the absence, 
or practical absence, of salivary glands. The primary 
function of lacrymal glands is to supply moisture for the 
surface of the eye, that of the salivary glands to supply 
moisture to the food: hence the absence of both in aquatic 
animals. Under the tough skin we find a very dense thick 
layer of fatty tissue or “‘blubber,” which is really the 
enormously hypertrophied panniculus adiposus. The por- 
poise has dispensed with its outer coating of hair to 
produce less friction and consequently greater speed, hence 
the warmth of the body is retained by “ blubber.” 
