Tue Evo.turionary SEQUENCE IN THE Coss 
Shelled cobs comprised by far the largest fraction of 
the maize remains found in Bat Cave. These included 
52 separate lots, totaling, as has already been stated, 766 
specimens. Of these, 471 were sufficiently well-preserved 
to be studied for a number of distinct botanical charac- 
teristics. 
Our method of studying the prehistoric cobs was to 
snap each cob in two, examining the two surfaces thus 
exposed under a dissecting microscope. ‘The number of 
characteristics which can be studied in the maize cob is 
truly astonishing. Those which we considered are listed 
in Table I. Further studies of the maize cob will un- 
doubtedly reveal other characteristics which can be uti- 
lized in comparing maize populations. Lenz (1948), for 
example, describes a ‘‘rachis flap’’ which is prominent in 
some varieties and relatively inconspicuous in others. 
The rachis flap was so erratically distributed in the Bat 
Cave specimens that we gave no serious attention to it. 
Nor did we attempt to measure rachilla length, another 
characteristic in which maize varieties differ considerably, 
according to Lenz (1948) and Cutler and Cutler (1948). 
However, some of the other characteristics which we did 
investigate, such as length and shape of the glumes, are 
strongly correlated with rachilla length, so that indirectly 
we undoubtedly took this character into account. 
The characteristics in which the specimens from the 
six strata are compared are described below. 
Length of Cob. This is a simple measurement made 
on all cobs which were intact with respect to length or 
so nearly intact that their original length could be esti- 
mated. The data in Table I show that there is little dif- 
ference in the mean length of the cobs in the first three 
strata. Thereafter, there is a more or less progressive in- 
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