70 Scientific Proceedings, Royal Dublin Society. 
by algze of a very deep green colour—a remarkable example of 
adaptation to unusual circumstances. Though much of the lava 
sheet has been removed by erosion, a few truncated conical hills 
show its former level and extent. ; 
Rosario mountain, a trachyte peak 5198 feet high (by boiling 
point), is worth a visit, as it gives anzextensive view. At its base 
there are gold mines, where the metal is extracted from hematite in 
primitive native mills called arrastras, consisting of shallow, paved, 
circular pits, round which heavy stones are dragged by mule 
power. On Rosario mountain was a7 curious mass of vegetation, 
moulded to the shape of a spouting waterfall; it extended from 
one rock-ledge to another forty feet higher, in a paraboloid form, 
so that the water would run over its surface in an even sheet. 
The mass was as dry as hay, but seemed to be a selaginella. 
There are several sorts of ferns here, which roll up tight in the 
dry season, and respond to a small shower of rain by immediately 
expanding the evergreen upper sides of their fronds. Deer and 
jaguars are common about Rosario. 
- Below Baca the river takes a sweep to the west, having been 
diverted by lava-flows from volcanoes near Chois, and it returns to 
its general direction near Toro; most of the intervening country 
has been swept clear of lava, exposing syenite. At Toro several 
hills, like bench-marks in an excavation, show the former level of 
the lava. The ranches here, are fenced by rows of single-stemmed 
cacti, growing in contact to a great height; they are only six 
inches thick, but absolutely unclimbable. A singular tree called 
Bebalama grows in the plain, it has slender stem, branches, and 
twigs of a bright-green colour, and showers of beautiful yellow 
flowers, but no leaves in March; the sheltered ravines contain 
some rubber-bearing plants, though they are not plentiful, owing 
to the long drought. The immense sahaura (Cereus giganteus) or 
pillar cactus of the Gila valley does not grow so far south. 
Between Sinaloita and Ocolome, on the river, there are outcrops 
of mica schist and slate, the general strike of the cleavage being 
a little west of north; below this the country becomes more level. 
At the town of Fuerte the river is 300 yards wide, with a rapid 
current over coarse sand, but only three or four feet deep. There 
is a colouring about the gorgeous sunsets of the plain which is 
peculiar to the shores of the Californian Gulf—hues of violet, 
