LIMITS OF HEREDITARY CONTROL 895 
The fourteenth and fifteenth cases appear in the sixth and ninth 
bands, respectively. 
Several of the cases of splitting are rather complicated, but not 
to such an extent as to render their classification uncertain. One 
of these is shown in fig. 13, and it will be noted that while the 
‘abnormality’ is clearly of the bilateral type, yet it is slightly com- 
plicated by having an additional splitting just to the right of the 
left-hand split. 
(3). Additions. The final class of band variations is additions, 
by which is meant the adding of a band or part of band from either 
of the shields lying adjacent to the banded region. Six cases of 
this type have been observed, and five of these are from the 
seapular shield. An excellent example of this type is seen in fig. 
19. The right half of the posterior row of scutes has dropped 
down from the shield and forms a perfect band on this side of 
the armor. One can follow the scutes of the added half-band 
across to the left side where they clearly form the posterior row 
of the scapular shield, so no question can exist regarding the origin 
of such ‘abnormalities.’ 
It is easy to imagine how a completion of the dropping would 
resuit in adding an entire new band to the banded region, and the 
four or five cases of ten-banded animals that we have observed 
may have acquired their extra band in this manner. However, 
it is possible that additions may take place from the pelvic shield; 
in fact, our sixth case of additions has probably come to exist in 
this way, because the pelvic shield of this particular specimen is 
foreshortened. It should be noted also that a ten-banded animal 
could be produced by a complete splitting of one of the nine regu- 
lar bands. 
In four of the seven cases of band variations, not classified in 
the above groups, not sufficient data were taken to permit an 
. exact determination of their characters; they are merely recorded 
as being ‘abnormal.’ Two of the remaining three are almost 
exactly the same, except that one is in the first band and the other 
intheninth. The latteris sketched in fig. 14. The ‘abnormality’ 
is located approximately in the middle of the band, and consists 
of a region of four double scutes. At first one would be inclined 
