156 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
large plain, seem to signify that the sea has retreated here more and 
more, and the products of its waters gradually surrendered to the firm 
land.” 
At Ponta d’Areia, Bahia. — Ponta d’Areia, the terminus of the Bahia 
e Minas Railway, stands on a sandy flat that reaches from the sea at the 
Barra de Caravellas up the river to the old city of Caravellas — a dis- 
tance of five kilometres. Following the line of the railway this same 
sandy plain continues to kilometre ten. This much of it I have 
examined, but the configuration of the country suggests that this 
sandy plain extends far up and down the coast — possibly as far as 
Prado. 
At Ponta d’Areia the plain has а maximum elevation of only 2.29 
metres above high tide; near Barra de Caravellas it is from 2.5 to 3 
metres, and at the city of Caravellas it is from 2 to 2.05 metres above 
tide. The profile of the railway is not available, otherwise the elevation 
of the landward margin of this plain might be given. 
This plain is not hummocky like a sand plain heaped up by winds 
upon a growing beach, but is characterized by long gentle slopes that 
are imperceptible to the eye, and by sudden changes of level like the 
materials of a sand bar. 
The upper part of these sands is generally of a grayish color darkened 
with organic matter, while at a depth of 0.2 to 0.4 metres they are of a 
yellow, almost an orange, color. 
I have spoken of these beds as sands: on top they generally are sands, 
but at a depth of a metre or so they are often sandy clays, so much so 
that they are used for making pottery, bricks, and tiles. I have not 
seen any false bedding in this formation. 
Everywhere over the plain these sands contain an abundance of ma- 
rine shells both entire and broken. They are brought to the surface by 
ants and other burrowing animals, and are found in the shallow railway 
cuts, in post-holes, and in wells. 
At one place between Ponta d’Areia and Caravellas in this formation 
I found also a piece of coral (Heliastrwa aperta) as large as one’s fist. 
I am not, however, without doubt about trusting this coral fragment. It 
was found within 300 metres of Pitonga, a little village of three or four 
cabins, and may have been dropped here by man. It is of а species used 
for making lime. 
At another place half-way between Ponta d’Areia and Barra de Cara- 
vellas I found in the debris thrown from a shallow pit dug in search of 
water one small specimen of coral (Astrangia solitaria). This specimen 
