The spiral-systematic ear, like its putative precursor 
the whorled-random ear, furnishes no evidence whatever 
of fusion. It does, however, have the aspect of a fusion 
product and especially is this true of eight-rowed ears in 
which the pairs of rows are distinctly separated with shal- 
low clefts or apparent lines of fissure in the cob corres- 
ponding to the lines of demarcation. Furthermore the 
sequence of sessile and pedicellate spikelets around the 
circumference, SSPPSSPP, sometimes encountered, is 
the kind of sequence which would be expected as the re- 
sult of fusion of two-ranked branches. Nevertheless there 
is neither evidence of fusion nor necessity for assuming 
that it has occurred. 
There is perhaps no single characteristic by which 
these two types of maize ears can always be distinguished 
from each other. Actually pure forms of either are prob- 
ably rare and intermediate forms are more common than 
the basic types. There are, however, several circum- 
stances usually associated with the two general types. 
The ‘‘pure’’ maize with its derivatives is the predomi- 
nating type in the Andean region of Peru, Bolivia and 
Ecuador and in the adjoining lowlands of South Amer- 
ica, particularly in Paraguay. It is also the predominat- 
ing type in the prehistoric maize of South America. The 
same or asimilar ear is found at high altitudes in Guate- 
mala and, also at high altitudes, in some localities in 
Mexico. 
The Tripsacum-contaminated maize is typical of most 
of North and Central America and of most of the low- 
lands of South America. 
It is realized that there is still no actual proof for the 
existence of “‘pure’’ and Tripsacum-contaminated maize. 
Nevertheless it is now reasonably certain that there are 
two basically different types of maize ears with more or 
less distinct patterns of geographical distribution. Since 
Eve 
