64 
MAMMALIA. 
the dirt was quietly removed. Within twenty-four hours a large and 
handsome Brewer’s Mole was found in the pipe. 
The modification of structure that adapts this animal to its peculiar 
mode of life affords a most remarkable example of animal specializa- 
tion. The conical head, terminating in a flexible cartilaginous 
snout, and unincumbered with external ears or eyes to catch the dirt, 
constitutes an effective wedge in forcing its way through narrow 
apertures ; the broad and powerful hands, whose fingers are united 
nearly to their very tips and armed with long and stout claws, supply 
the means by which the motive power is applied, and serve to force 
the earth away laterally to admit the wedge-like head ; while the ap- 
parent absence of neck, due to the enormous development of muscles 
in connection with the shoulder-girdle, the retention of the entire 
arm and forearm within the skin, the short and compact body, and 
the covering of soft, short, and glossy tur, tend to decrease to a 
minimum the frictional resistance against the solid medium through 
which it moves. In fact, it presents a most extraordinary model of a 
machine adapted for rapid and continued progress through the earth. 
The mole does not, and cannot, dig a hole, in the same sense as 
other mammals that engage in this occupation, either in the construc- 
tion of burrows or in the pursuit ot prey. When a fox or a wood- 
chuck digs into the ground, the anterior extremities are brought 
forward, downward, and backward, the plane of motion being almost 
vertical : while the Mole, on the other hand, in making its excava- 
tions, carries its hands forward, outward, and backward, so that 
the plane of motion is nearly horizontal. The movement is almost 
precisely like that of a man in the act of swimming, and the simile is 
still closer from the fact that the Mole brings the backs of his hands 
together in carrying them forward, always keeping the palmar 
surfaces outward and the thumbs below. Indeed, when taken from 
the earth and placed upon a hard floor, it does not tread upon the 
palmar aspect of its fore-feet, as other animals do, but runs along on 
the sides of its thumbs, with the broad hands turned up edgewise. 
