Nobogame teosinte and on at least five chromosomes of 
Durango teosinte. Rogers (48) has found linkages be- 
tween glume score, which is mainly concerned with in- 
duration, and marker genes in hybrids involving five 
varieties of teosinte, the strongest linkage in four of the 
five hybrids being with the marker gene on chromosome 
4. In view of these facts, the occurrence of highly ligni- 
fied specimens of prehistoric cobs immediately raises 
the suspicion of previous contamination with teosinte. 
When lignification is accompanied, as it is in some speci- 
mens, with single spikelets, also a teosinte characteristic, 
the suspicion virtually becomes a fact. 
Tripsacoid prehistoric maize was first clearly recognized 
in a collection of archaeological corn from Bat Cave, a 
rock shelter in New Mexico excavated by Mr. Herbert 
Dick (87). Weatherwax (52) was skeptical of this evi- 
dence and, since he had seen illustrations of only a limited 
number of specimens, his skepticism may have been war- 
ranted. The data are however quite convincing. Of the 
471 cobs studied, 250 or more than half were scored as 
being intermediate or strong in teosinte introgression. 
The fact that all but two of these were found in the four 
upper levels of the deposit was regarded as highly signifi- 
cant and as an indication that teosinte admixture appeared 
on the scene only after maize cultivation had become 
well established in the area in which Bat Cave is located. 
The second expedition to Bat Cave by Mr. Dick turned 
up many additional tripsacoid specimens not yet de- 
scribed and has confirmed one of the most significant 
features of the collection from the first expedition: non- 
tripsacoid cobs in the early levels, a high frequency of 
tripsacoid cobs in the later ones. 
In addition to those found in the two Bat Cave expe- 
ditions, tripsacoid cobs have now been identified in col- 
lections from the following caves: Richards and ‘Tonto 
[ 397 ] 
