| 1014 On the Shells of the Colorado Desert [October, 
organic remains which I saw were some fragments of Lepidoden- 
dron from the strata immediately overlying the coal bed atthe Ar — 
roio dos Ratos mine. These were much compressed and broken, — 
but the generic characters were still clearly recognizable, and 
they are sufficient to establish the Paleozoic age of the beds. Be- : 
yond this I can only give it as my decided opinion that the coal 
rocks are of the Carboniferous period, and probably coeval with ne 
the Santa Catharina coal formations. e 
The question arises whether the coal beds were laid down in 
one sheet, which was subsequently folded as the ridges were — 
formed, and then denuded over their tops; or whether the ridges 
already existed when the coal beds were formed, the latter having a 
been deposited in the valleys between them? It appears to mè 
that the ridges were partly raised before the coal beds were 
formed; that the latter were first laid down in the hollows, but 
gradually the upper beds extended over the granite hills. Subse- — 
The original continuity of the beds appears to be proven by the : ; 
general conformity of the. sections in the three basins which I 7 
have described ; but the inclination of the coal rocks is eve- 
where much less than that of the sides of the granite ridges. 
Another question is important in an economical sense: Are 
there other beds of coal below that which is now worked in the : 
Arroio dos. Ratos mine? I think not. It seems certain that the 
section in this basin is the same as that at Dous Passaros, whet 
- the coal rocks lie directly on the granite, and no trace is seen 
another coal bed below the iron-ore layer. As it appears 
this latter bed has been cut in excavations made below the coa! 
believe that further borings would only show layers of sandston® 
followed, at no great depth, by the granite. 
0: AND 
ON THE SHELLS OF THE COLORADO DESERT © — 
THE REGION FARTHER EAST? 
BY ROBERT E.. C. STEARNS. 
Part I—Tue Puysas oF INDIO. 
BOUT four years ago I called attention to certain 
of fossil shells contained in a lump of earth taken 
of Sciences, June » 
1 This paper was read before the California Academy 
It may be regarded as supplementary to my “ Remarks on 
Fo 
Colorado desert,” published in the NATURALIST, Vol. XII, March, 1879- 
