358 JAMES ROLLIN SLONAKER 
mm. The above author evidently failed to recognize that the 
‘‘eylindrical form of the body”’ was due to most of the bones of the 
fore limbs being enclosed in the body integument rather than to 
the length of the ribs. 
The pelvic girdle also shows marked modifications as com- 
pared with the mammalian type. As shown above, the pectoral 
girdle and the bones of the fore limbs are greatly enlarged and 
strengthened. In the pelvic girdle the reverse condition obtains, 
resulting in a great reduction in the size of the pelvis. This is 
TABLE 2 
Showing the lengths in mm. of the ribs, together with their bony and cartilaginous 
portions of Scalops aquaticus 
NUMBER OF RIB BONY PART CARTILAGINOUS PART TOTAL LENGTH 
1 7.0 3.8 10.8 
2 8.0 7.7 15.7 
3 11.3 9.0 20.3 
4 17.0 11.5 28.5 
5 18.5 12.0 30.5 
6 23 7, 14.5 38.2 
7 26.0 18.3 44.3 
8 26.0 17.5 43.5 
9 25.0 16.5 41.0 
10 24.5 Ai igslGiO 40.5 
u 22.0 15.5 37.5 
12 18.0 14.5 32.5 
13 16.0 14.0 30.0 
14 12.0 12.0 24.0 
especially noticeable in the diameter. As previously stated, this 
reduction in size is necessary to permit the bulky anterior por- 
tion to pass the posterior part when the mole turns in its bur- 
row. Accompanying this reduction in diameter the pelvis has 
taken a position almost parallel to the vertebral column. Ac- 
cording to Taylor (14), this arrangement would tend to increase 
the flexibility of the animal, for he says: “‘In aquatic animals 
increased flexibility of the vertebral column is associated with a 
pelvis having a position more nearly parallel to the vertebral 
column than in land forms. The pelvis is also more extended 
