MUSCULAR SYSTEM OF THE VERTEBRATA. 45 



raised, and the fore-arm extended, a considerable extent of sur- 

 face thereby gained ; the entire member being then forcibly 

 depressed, the resistance which it receives from the air, effects the 

 elevation of the bird; velocity of flight depends upon the rapidity 

 with which these strokes succeed each other. The eider-duck is 

 supposed to fly 90 miles an hour; the hawk 150, and everyone 

 has heard of the falcon belonging to Henry IV. king of France, 

 flying in one day from Fontainbleau to Malta, a distance of 1350 

 miles. 



MAMMALIA. 



Some of the animals composing this class are destined to move 

 like fishes through a watery element, some to fly through the air 

 like the feathered tribes, some to climb treess, some to dig and 

 burrow in the earth, and others to walk upon its surface. Habits 

 so diversified bespeak corresponding diversities of muscular arrange- 

 ment. Many approximations to the human type present themselves 

 on the one hand, and indisputable recurrences of simpler forms on 

 the other. The fleshy portions of the muscles are generally large 

 and plump, proportioned to the size of the body, or the massive 

 bones of the skeleton. The respiration being here less extensive, 

 and the circulation more slow, than in birds, the temperature is 

 lower, the muscular fibre less dense, and the tendons less prone to 

 undergo ossific changes. 



The arrangement of the muscles in the cetacea nearly coincides 

 with that in fishes, the latter moving horizontally, the former chiefly 

 in a verticle direction. The muscles of the ribs, spine, pharynx, 

 os hyoides, and exterior nares a are well developed, those of the pelvis 

 and posterior extremities disappear with those parts, and the muscles 

 of the anterior extremities are curtailed and simplified, least so, 

 however, in the phytophagous cetacea. The large herbivorous 

 quadrupeds require strong muscles to move their massive and 

 heavy trunks, and the active and predatory habits of the carnivora 

 demand a still greater development of this system. In theruminan- 

 tia, pachydermata, and those animals without clavicles, the anterior 

 extremities are placed under the trunk, which is suspended between 

 their long vertical scapulas by the great serrati muscles, in many 

 instances prodigiously developed. The buffalo, the bull, and others 

 of the ruminants, with many of the pachyderms, have the muscles 

 of the neck large and powerful to move their heavy heads, which 

 are often armed with large teeth, tusks, a proboscis, or huge horns. 

 The external muscles of the ear are greatly developed in many of 

 the herbivorous quadrupeds, and the muscles of the nose in the 

 hog tribe. 



The panniculus carnosus. which is thin, and finely spread over 

 the trunks of the pachydermata, is strong and fleshy in the soft 

 skinned ruminantia, where it is attached to the humerus and to the 

 femur. In the mammalia covered with spines, as the echidnia, the 



