894. H. H. NEWMAN AND J. THOMAS PATTERSON 
fusion of the two bands occurs on both sides of the armor. A very 
good example of this latter type is shown in fig. 11 in which seven 
scutes are involved on the left side and four on the right. 
The unilateral type occurs 25 times in the 31 cases of fusion, 
and appears 15 times on the left side and 10 on the right. It is 
distributed as follows among the several bands: 18 times between 
bands 1 and 2; 3 times between bands 8 and 9; and once each 
between bands 2 and 3, 4 and 5, 5 and 6, 6 and 7. In almost 
every case of unilateral fusion the scutes at the extreme lateral 
margins of the bands are involved, and in only a few specimens is 
it situated well within the margin (e.g., in fig. 18). 
The six remaining cases of fusion are all of the bilateral type, 
and in each instance the two fusions are practically symmetrical, 
both as to position and extent. This is true even when they are 
situated toward the median line of the armor. All the bilateral 
fusions observed are between bands one and two. 
(2). Splittings. The second kind of atypical band variation 
is the splitting, which as already stated consists of a transverse 
division of the elements to give rise to two bands. It is not 
always an easy matter to determine, especially in complex cases 
where two bands seem to be greatly confused, whether we are deal- 
ing with a fusion or a splitting; but a rather safe, though not uni- 
versal, rule to follow is to count the elements in each row of the 
double regions, and if these be equal in numbers it is safe to decide 
that one is dealing with a splitting (fig. 12). 
Using this as our principal method of determination we have 
classified sixteen specimens as belonging to this group. Five of 
these are unilateral (three on the left and two on the right) and 
eleven bilateral. One of the most striking features of the latter 
type is the strong tendency to be almost bilaterally symmetrical. 
For example in fig. 12 is shown one in which the splitting begins in 
the seventh scute on each side, and the specimen fails to show 
symmetry in its bilaterality only in having the splitting slightly 
less extensive on the right than on the left side. Another point 
worthy of note is the fact that splittings are confined almost en- 
tirely to the first band; thirteen of the fifteen cases occurring here. 
