120 REPORT—1840. 
small valley upwards of a league in length, and about half a league 
across in its widest part. The deposit of fossil fishes (from which those 
now exhibited were chiefly obtained), is in an open place of the gently 
sloping ridge north of the villa; there the ground is covered with 
great abundance of rounded stones of various sizes, from that of an 
egg, to blocks of several feet in circumference, consisting of a light- 
coloured, rather impure limestone, in which lines of bedding may 
often be perceived, and sometimes minute shells. They split very 
easily, and contain portions of fishes in a more or less perfect state ; 
by far the greatest number, however, being so much broken, that it is 
with considerable difficulty that tolerably perfect specimens can be 
obtained. The space to which these limestone nodules are confined, 
is not more than one hundred yards square, and scarcely any other 
kind of stones is to be found among them; but on every side of it, the 
ground is covered with other rounded pebbles of sandstone, similar 
to the rock of which the Serra is composed. Three other deposits of 
fishes occur in the neighbourhood, one about half a league to the 
south, a second at Macapé, five leagues to the east of Jardim, and a 
third at Mundo Novo, three leagues to the west. These are all on the 
declivity of the low hills, between the valley and the Serra, and per- 
fectly resemble the one described, in consisting only of the rounded 
fossiliferous limestone nodules. 
On breaking these nodules, many of them exhibit abundance of a 
minute bivalve shell. At Mundo Novo Mr.G. found in the same nodule 
avery perfect specimen of what he believes is a species of Turrilites,about 
14 inch long, and a single valve of a Venus about half an inch in length, 
and in very excellent preservation. He was told by a person at 
Jardim, that a few years ago he found a small serpent coiled up ina 
stone which he had split, but this, no doubt, was a species of Ammo- 
nites. In the several hundred stones, however, which he broke in 
search of fish,she met with nothing of this description. These speci- 
mens Mr. G. had not sent over; neither has he accompanied those 
submitted to the Section by any of the sandstone of the Serra de 
Araripe; but from the fact communicated by M. Agassiz, that he has 
not yet met with cycloid fishes in any older formation than the chalk, 
and as far as can be inferred from the minute bivalves, it is probable 
that the sandstone hills in which the deposits occur, belong to that 
geological epoch. He states that he could nowhere find in the neigh- 
bourhood of Barra do Jardim any limestone in situ. This cireum- 
stance, taken in conjunction with the fact that the fossiliferous 
nodules show indications of stratification, and are found in detached 
localities, and not intermixed with those of the sandstone, which 
surrounds them on every side, leads to the conclusion that they occur 
as a bed or layer of detached concretions in the sandstone, each fish, 
or portion of one (for many seem to have been imbedded after being 
broken), having attracted round it a sufficient quantity of the lime 
disseminated through the mass to form a nodule*. 
* This paper has since been published entire in the New Edinburgh Philo- 
sophical Journal for January 1841, with a Notice of the Fossil Fishes by Pro- 
fessor Agassiz. 
