1889. ] NEW YORK ACADEMY OF SCIENCES. 81 
lum, Gray, Helianthus Mazximiliani, Schrader, and Parietaria. 
debilis, Forst., are among the most characteristic of this diverse 
flora. Of these, the last six may be mentioned as becoming 
more common as we descend, and being really plants of the 
lower districts. Upon the rocky margins of these canyons, in 
localities especially exposed to the sweeping storms, occurs the 
peculiar Spirea cespitosa, Nutt.—a stout shrub, with stem often 
an inch and a half in diameter, yet its uppermost portions are 
rarely more than an inch and a half above the rocks on which it 
lies closely prostrate. In its company are usually some shrubby 
Eriogonums, notably /. deflecum, Torr., F. microthecum, Nutt., 
and £. flavum, Nutt. 
Continuing our descent of such a canyon until it emerges 
from the forest, there is an open, but usually grassy plain of 
greater or less width to traverse, and we stand upon the jagged 
edge of the plateaus, and gaze into some basin from one to two 
thousand feet deep, and out across the desert plains which con- 
stitute the third region of which I have spoken. At nearly all 
points upon the edge of this plateau, we find such an abrupt 
descent. Its passage is rendered still more laborious by the 
dense tangle of scrub oaks which cover it towards the summit. 
A consideration of the interesting flora of this lower region 
forms no part of the present paper. 
On the explorations conducted in this forest in 1883, I was 
accompanied by Mr. Randall Spaulding, to whose exceptional 
skill in photography we are indebted for the series of views with 
which my paper has been illustrated, and by Mr. Charles M. 
Dayis and my brother, Mr. Wm. 8S. Rusby. Through their 
keen eyesight my list has been enriched with many of its species. 
The subject was further discussed by the PRESIDENT, who 
referred to his own travels in the same region some years before. 
He described a severe snow-storm on the table-land, with a fall 
of eight inches in depth, gave reminiscences of bear-hunting in 
the forests, and alluded to the cliff dwellings in the San Juan 
valley, and the remarkable and interesting scenery produced by 
the abundant growth, in many of the valleys, of yuccas, cacti, 
and century-plants. 
