the rachises and glumes which are highly indurated. 
Cobs of this race are probably the product of hybridiza- 
tion of Chapalote with corn’s closest relative, teosinte. 
Specimens of teosinte and corn-teosinte hybrids were 
found among the prehistoric vegetal remains. 
The Tripsacoid Chapalote appeared first in the Guerra 
phase but at a later level than the Karly Chapalote. A 
single cob occurred in level 5 and the subrace was well 
established (126 cobs) in level 4b which represents the 
end of the Guerra phase probably about 1500-1200 B.C. 
This corn became the predominating type in the two 
succeeding phases, 1200 B.C.—A.D. 800, and thereafter 
was gradually replaced by other races, persisting, how- 
ever, aS a prominent component in the complex until 
A.D. 1800, after the arrival of the Spaniards. 
Chapalote. (Plate VIII, B). Cobs of a type quite 
similar to those of modern Chapalote appeared first in 
the Mesa de Guaje phase, 1200-400 B.C. They increased 
in frequency in the Palmillas phase (14.5 percent of all 
cobs) and continued to maintain approximately this fre- 
quency until the end of the series. A total of 361 cobs 
were assigned to this category. 
Wellhausen ef al. (1952) collected modern Chapalote 
in only two states in Mexico, Sinaloa and Sonora, but 
as pointed out above it must at one time have been 
much more widespread. 
Breve de Padilla, (Plate X, A). Making its first ap- 
pearance only slightly later than modern Chapalote— 
level 4a of the Mesa de Guaje phase—is a race called 
Breve de Padilla by Wellhausen (unpublished). 
The origin of this race is not definitely known. Its 
cobs are longer and thicker than those of Chapalote and 
it may be the product of hybridization between Chapa- 
lote and Harinoso de Ocho, a race originally from South 
America and still found sporadically in western Mexico. 
[ 40 ] 
