156 BULLJITIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



large plain, seem to signify that the sea has retreated here more and 

 m^re, 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 f;u- up and down the coast — possibly as far as 

 Prado. 



At Ponta d'Areia the plain has a maximum elevation of only 2.29 

 metres above high tide ; near Barra de Caravellas it is from 2.5 to 3 

 metises, 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 {Heliastrma 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 a species used 

 for making lime. 



At another place half-way between Ponta d'Areia and Barra de Cara- 

 vellas I found in tlie debris thrown from a shallow pit dug in search of 

 water one small specimen of coral (Astrangia soliiaria). This specimen 



