of maize, although clearly related to each other such as 
Chapalote and Nal-Tel, had early become adapted to 
different highland and lowland environments and tended 
to spread within these ‘“‘ecological zones.’’ This in turn 
suggests that perhaps it was only at the latest prehistoric 
levels that the culture and agriculture of the highlands 
and lowlands merged to become the single ‘‘culture 
area’’ Meso-America. 
Pre-Chapalote. (Plate VIII, A). Following the no- 
menclature employed in our earlier descriptions of pre- 
historic maize (Mangelsdorf et al., 1956; Mangelsdorf 
and Lister, 1956) we have called the earliest corn un- 
covered in Romero’s Cave Pre-Chapalote. The cobs of 
this subrace have the same tapering shape as those of the 
modern Chapalote but are much smaller. None are as 
small, however, as the prehistoric wild corn from ‘Tehua- 
cin Valley. We assume that even the earliest corn from 
the Tamaulipas caves is cultivated corn. 
Pre-Chapalote makes its first appearance (a single cob) 
in the Flacco phase of Valenzuela’s Cave dated at 2850— 
1850 B.C. It appears last in the Mesa de Guaje phase 
dated at 1200-400 B.C. The total number of cobs of 
this subrace is 17. 
Early Chapalote. (Plate VIII, A). The cobs of this 
subrace, comprising 133 specimens, are intermediate in 
size between those of Pre-Chapalote and modern Chap- 
alote. In other respects the cobs are quite similar to 
those of modern Chapalote. Cobs of this subrace ap- 
peared first in the Guerra phase dated at 1850-1200 B.C. 
and last in the San Lorenzo phase, A.D. 1050-1450. 
Tripsacoid Chapalote. (Plate XI, A). Slightly more 
than half of all identified cobs, 1546 specimens, were 
assigned to a subrace which we called Tripsacoid Chap- 
alote. The cobs are quite similar to those of Chapalote 
but differ in the induration of their tissues, especially of 
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