Several thousand kernels of this type are available from 
Levels 5 and 6; almost all of these are very similar to 
the kernels of modern Chapalote in their size, shape, and 
brown pericarp color. Chapalote is the only race in Mex- 
ico which has brown pericarp color. The resemblance 
between the kernels of modern Chapalote and the archae- 
ological specimens is well illustrated in Plate XX XIX, 
inset. 
Tripsacoid Maize. Beginning with Level 2 in Swallow 
Cave, there is evidence of maize which has been modified 
by teosinte introgression. Included in this type, desig- 
nated as ‘‘T'ripsacoid,’’ are small cobs with strongly in- 
durated glumes and occasional single spikelets or partially 
aborted second, or pedicellate, spikelets. There is even 
more evidence of this introgression in certain of the speci- 
mens from the surface layer, some of which have strongly 
indurated crateriform lower glumes, which are set at right 
angles to the rachis like the teeth of a coarse wood rasp. 
Glumes of this kind are quite characteristic of certain 
segregates from maize-teosinte hybrids, and some of these 
archaeological specimens, like those described by Galinat 
et al (1956), can be almost exactly duplicated by modern 
specimens obtained from experimental cultures. The 
combination of indurated glumes and single or partially 
aborted spikelets leaves little doubt that there has been 
introgression of teosinte into the maize of Chihuahua in 
prehistoric times. 'Teosinte is fairly common in western 
Mexico and has been collected in the state of Chihuahua. 
Furthermore, Lumholtz reports that the Indians of west- 
ern Mexico practiced the custom of interplanting maize 
and maizillo (probably teosinte) for the purpose of im- 
proving their maize. Plate X LI shows Tripsacoid cobs 
from Swallow Cave. The same evidence of teosinte in- 
trogression is to be found in the cobs from other locali- 
ties. 
[ 164 | 
