20G 
THE GEOLOGIST. 
we must consider the Pointe a Pierre deposits as undoubtedly equal 
to or older than the true chalk. 
Kumerous fragments of an oyster somewhat like Osirea ccrmiata, 
a fossil of the Lower Greensand, are found with the Trigonia. I 
have not however been able to obtain a perfect specimen. At the 
same locality I have found oysters referable, perhaps, to two other 
species. One of these is a good deal like the recent Ostrea edulis, 
and one of my specimens shows the markings of the hinge cartilage 
very distinctly. I have also found a single valve of a deeply sulcated 
bivalve, which may be an Avicula, but which presents some resem- 
blance to a fossil described by Von Buch as a Pecten under the name 
of Fecten cdatus* My specimen, however, has fewer sulcations than 
the shell described by A^on Buch, and the absence of wings makes 
the determination somewhat uncertain. It is possible, however, that 
the shell in question may be a j-oung specimen of P. aJatus. 
Gasteropoda are also represented among the fossils from Pointe a 
Pierre, but the specimens are generally so imperfect as to render the 
determination of their relationsliijis difficult. A cast in my possession, 
upwards of 2 inches in length from the apex to the peristome, seems 
to be of a naticoid type. Another cast, which has some shelly mat- 
ter remaining on it, is very like a cast figured by Von Buch as a 
Eostellaria, and may belong to the same species.f 
A single valve, embedded in a calcareous nodule, from Pointe a 
Pierre, appears to have belonged to a Plagiostoma, while a massive 
gibbous valve about 2^ inches in length, has some of the characters 
of a Cytherea ; but that genus is not common in rocks of such ancient 
date. Amongst the fossils collected by me, are several other frag- 
ments of Mollusca, which appear to be indeterminable. Still, though 
there is much doubt respecting a great part of the fossils yet col- 
lected from these deposits in Trinidad, enough has been discovered 
respecting them to confer a character of greater certainty on the pre- 
sumption of the age of the Older Parian deposits in this island than 
has been previously attained to. 
All the fossils I have been able to obtain from Pointe a Pierre 
have been from the beach ; consequently, they are usually much 
worn, and it is hardly possible to ascertain from what portion of the 
group they have been derived. The Trigonia and the oysters are 
tolerably well preserved, as far as their structure goes ; but the shells 
of the Gasteropoda have nearly disappeared. The thick and massive 
character of the shells is worth notice, and it prevails alike in all the 
specimens in which the test is preserved. 
Prom what I have said in this paper, it will be seen that the pa- 
]«ontological evidence is in favour of Mr. Etheridge's view;}; of the 
age of the deposits termed " Older Parian " by the Government geo- 
logists. Until, however, more fossils can be obtained, and their 
position in the series better determined, it will be as well to leave 
* Vou Buch, ' Petrifactions reciielJics pnr Humboldt,' pi. i. figs. 1, 2, 3, 4. 
t Von Buch, ' Petrifications,' pi. ii. fig. 27. 
X Keport on the Geology of Trinidad, p. 163. 
