LIMITS OF HEREDITARY CONTROL 893 
hair scutes, are inherited in the blended fashion is shown by a 
comparison of the counts of the mothers and those of the foetuses. 
In nearly every case the latter show marked divergences from the 
former, which would seem to indicate a total lack of exclusiveness 
about the inheritance. 
Attention might also be called to the fact that in this set three 
individuals have almost identically the same number of scutes 
while the fourth has decidedly more. 
C. Band ‘abnormalities’ in the species; their distribution and 
frequency 
The atypical variations in the bands consist primarily of extra 
or supernumerary bands or parts of bands, and show a rather 
marked degree of regularity in that they occur repeatedly in about 
the same regions of the armor. They are found most frequently 
in the first or second band, or in both, and may occasionally be 
seen in the region of the eighth or ninth band, but rarely appear 
in bands three to seven. Their frequency has been determined 
from a study of 1768 specimens, in which 60 are abnormal, or 
about 3.4 per cent of the total number of individuals examined. 
On account of the apparent nature of their origin, as well as 
for convenience in description, we have chosen to consider these 
‘abnormalities’ under three headings, as follows: (1) Fusions, in 
which parts of two bands have united to form a single structure; 
(2) Splittings, in which a series of elements of a band have divided 
transversely to produce a double row; (3) Additions, in which a 
band or part of band, either from the scapular or pelvic shield, 
has been added to the thoraco-lumbar shield, thereby increasing 
the banded region, and in case of the contribution or an entire 
band, producing a ten-banded animal. 
(1). Fusions. This kind of variation is found in 31 of the 60 
‘abnormal’ specimens, or in more than fifty per cent of the cases. 
It usually expresses itself in one of two ways. In one type two 
adjacent bands have their scutes at one side of the armor united 
to form a single structure. This type may be spoken of as ‘uni- 
lateral,’ in contrast to the second or ‘bilateral’ type, in which the 
