consisted (and likewise from lesser heights) of very young and small
specimens of the still living Concholepas, Trochus, Patellae, Crepidulae,
and of Mytilus Magellanicus (?) (Mr. Cuming informs me that he does not
think this species identical with, though closely resembling, the true M.
Magellanicus of the southern and eastern coast of South America; it lives
abundantly on the coast of Chile.): several of these shells were under a
quarter of an inch in their greatest diameter. My attention was called to
this circumstance by a native fisherman, whom I took to look at these
shell-beds; and he ridiculed the notion of such small shells having been
brought up for food; nor could some of the species have adhered when alive
to other larger shells. On another hill, some miles distant, and 648 feet
high, I found shells of the Concholepas and Trochus, perfect, though very
old, with fragments of Mytilus Chiloensis, all embedded in reddish-brown
mould: I also found these same species, with fragments of an Echinus and of
Balanus psittacus, on a hill 1,000 feet high. Above this height, shells
became very rare, though on a hill 1,300 feet high (Measured by the
barometer: the highest point in the range behind Valparaiso I found to be
1,626 feet above the level of the sea.), I collected the Concholepas,
Trochus, Fissurella, and a Patella. At these greater heights the shells are
almost invariably embedded in mould, and sometimes are exposed only by
tearing up bushes. These shells obviously had a very much more ancient
appearance than those from the lesser heights; the apices of the Trochi
were often worn down; the little holes made by burrowing animals were
greatly enlarged; and the Concholepas was often perforated quite through,
owing to the inner plates of shell having scaled off.

Many of these shells, as I have said, were packed in, and were quite filled
with, blackish or reddish-brown earth, resting on the granitic detritus. I
did not doubt until lately that this mould was of purely terrestrial
origin, when with a microscope examining some of it from the inside of a