Purpura labiosa, Gray ; recent at Valparaiso.*
Monoceros crassilabrum, L am .; recent at Valparaiso, &c.
Monoceros crassilabrum v a r.; recent at Valparaiso, &c.
Concholepas Peruviana, L am .; recent on the whole line of the Pacific side of the
South American coast. Two specimens, each with balani attached, the young of B.
psittacus.
With respect to the strata designated as marl and sand-stone, the collection made
by Lieutenant Belcher affords no evidence that is decisive of their age and character.
The marl and sand-stone seem to be tertiary, and the imperfect coal included in them
a tertiary lignite ; the petrified wood perforated by the teredo has more the appearance
of fossil wood from the London clay than from any secondary stratum. The ammonite
mentioned by Lieutenant Belcher is the only fossil indicative of strata of secondary
formation. I t is much to be regretted that two vertebrae found with this ammonite,
and also a vertebra six inches in diameter found near Point Parra, bave been mislaid.
I t is probable that great part of the extensive deposits coloured as alluvial, particularly
those at a distance from any existing rivers, on the summits of hills, and on elevated
table lands, are either tertiary or diluvial; but no observations were made
sufficiently minute to establish any certain conclusions upon this point.—E d .
u
E X T R A C T F R O M T H E N O T E S O F M R . C O L L I E .
The form of the Bay of Concepcion is oblong, about eight miles by six, extending
in its longest axis nearly north and south (see map, pi. I I . Geology). The land rises
from the sea, towards the entrance, in perpendicular and high cliffs, which gradually
diminish towards the head of the bay, where a long and low sandy beach is backed by
low marshes and meadows. Near the entrance of the bay, the Island of Quinquina
rises in bold and frequently inaccessible precipices, and is nearly connected by a subaqueous
reef with the northern extremity of the peninsula that forms the western shore
of the Bay of Concepcion, and separates it from the sea. A t the extremity of this
peninsula is a bed of green-stone.
The Island of Quiriquina exhibits clay-slate near its north-eastern extremity, but
its main body is composed of sand-stone and alluvial deposits. On its southern end we
find loosely aggregated sand, and large and small rolled stones, united more or less
firmly by calcareous cement. Tbe small stones are chiefly slate, green-stone, quartz,
and lime-stone. A calcareous marl forms the lower part of the east cliff of this island
in severai places. In some parts, also, beds of broken and petrified shells compose the
beach. A great part of the western shore of the island is so perpendicular that, having
once got on the top of the high land, it is impossible to descend and examine the base.
II i i
• There are in the collection some other specimens of a Purpura also found recent a t Valparaiso, and considered
by some to be Purpura labiosa in an advanced stage o f growth. Tlie difference, however, is so striking as to warrant
the inquiry, w hether these specimens are not undescribed, and specifically distinct from Purpura labiosa.