140 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. | 
choked with sands thrown up across them by the waves, while their 
upper portions have been filled up with silts from the land, and with 
organic matter. There is a large number of small rivers whose lower 
courses have had this history. Only a few of them need be mentioned. 
Rio Спада, at the bound- 
ary between the State of 
Parahyba and Rio Grande 
do Norte, has a broad flat 
bottom filled with sand, ly- 
ing between rather steep- | 
faced hills. 
Rio Sibaüma, a small | 
stream north of the Cun- | 
Taguarip е, as 
hahú, has a similar topog- 
raphy about its mouth. 
The Pirangy, though al- 
most closed by a high sand- 
bank, has essentially the 
same general topography. 
In the State of Parahyba 
we have similar forms at 
the mouth of the Mirirí, 
north of the capital, and 
the Grahú, south of the cap- 
ital, mot to mention the 
larger streams. In the 
State of Pernambuco simi- 
Sketch of the topography of a part of Rio Jaguaripe, state of Bahia. 
lar forms are common, 
though often modified by 
~ 
having the flat coast sands 
f built out beyond the steeper 
bluffs, thus merging the flat 
river valleys into the flat 
sandy coast plains. 
If good maps of them were available, some of the rivers about Bahia, 
the Jaguaripe, for instance, would illustrate this matter beautifully. The 
Jaguaripe, however, is very poorly shown upon the hydrographic charts. 
The sketch-map (Fig. 77), mostly constructed on the spot, will give, not 
the exact form, but rather an idea of the generalized features of a portion 
of the region. 
