336 JAMES ROLLIN SLONAKER 
common mole, Scapanus latimanus, of the central California 
coast region. 
The absence of light has resulted in degeneration of the eyes 
to such a very rudimentary condition that they are doubtless 
able to function only in perceiving the difference between light 
and darkness. These structures have been previously described 
(Slonaker, ’02). To compensate for this deficiency special 
touch organs have been developed in the snout and margins of 
the forefeet. 
The manner of its subterranean locomotion necessitates very 
powerful fore limbs and pectoral girdle to excavate the burrow. 
To accomplish this a marked increase in size, accompanied by 
many changes in form of these parts has been brought about. 
This great increase in size of the pectoral girdle and fore limbs 
has made this region of the body very bulky. In order that the 
mole may turn in its burrow and go in the opposite direction, it 
must be able to get this bulky anterior portion by the posterior 
part of its body. This brings about the reduction of the pelvic 
girdle and posterior limbs. This reduction of the pelvis has been 
so great and the pelvic outlet has become so small that the 
urogenital and alimentary tracts cannot pass through it. These 
canals are therefore excluded and pass wholly ventral to the 
pubic symphysis. These modifications will be described in detail 
later on. 
In order to make a definite correlation between the various 
modified structures in the mole and its activities and habits, it 
will be necessary to describe the latter in some detail. 
The moles are widely distributed and are found in almost all 
warm and temperate regions with humid climate. Regardless of 
this wide distribution, there is a remarkably close resemblance 
in their structure. The genera of different continents show a 
greater difference than those of the same continent. The five 
genera into which True (’97) divides the moles of America show 
some characteristic distinctions from the European mole, Talpa 
europaea. 
The European mole has been known to scientists for a long 
time. The earliest mention of it which I have found is in Konrad 
