224 Bulletin of Laboratories of Denison University. [Voi. xi. 
The Fauna of the Pleistocene. 
Little has been done in the collection of material for the 
study of the fossil remains of the pleistocene period. From 
many parts of the territory remains of the mammoth have been 
collected. In depressions of the great San Augustine plains 
east of Datil large numbers of teeth and bones are found where 
the great mammals were mired while drinking. It would appear 
that the period during which these elephants roamed our plains 
has not long passed. In the flood plain of the Rio Grande near 
Bernalillo several teeth have been found and one fine example 
is in the university museum. Several small gasteropod shells 
were taken from the river clays near Algodones and among 
these Mr. E. H. Ashman identified Sacciura overa, Say and 
Leucocheila fallox, Say. Doubtless many interesting forms 
will reward a diligent search. 
Petrography. 
In the region covered by the map there are comparatively 
few eruptive rocks and these belong to the later series. 
Basalts. 
Remarkable uniformity characterizes the basalts of this re- 
gion though they pass from the extreme of scoriaceous to mas- 
sive and amygdaloidal types. The chemical composition seems 
to have been very constant. Dutton and other writers report 
two distinct periods of basaltic flow but we have so far encount- 
ered no evidence of such an interval between the later and 
earlier flows as he indicates, in this region. The flows are all 
post-Tertiary and well preserved. Successive flows occurred and 
intervals are filled with volcanic sand and tufa but there is no 
evidence of long periods intervening. 
I. Basalt from the Albuquerque voleanoes. These cones, as 
described above, are conspicuous features in the landscape as 
seen from Albuquerque and break the uniformity of the west- 
ern horizon. 
The sample is somewhat vesicular but between the blebs 
the structure is compact and but slightly amygdaloidal. The 
