222 MOLLUSCA. 
with a rusty coating, as is most commonly the case with all shells 
found at the mouths of rivers in brackish waters. When perfect, it is 
of a light shining brown, clouded with black. 
Length about an inch and a half. 
Obtained near the mouth of the harbour of Rio Janeiro. Couthouy. 
Figures 266, 266 a, two views of the animal, with the shell. 
Bua piapHana (Couthouy, MS.) 
Testa fragilis, lucida, ventricosa, dilute cornea, transverse striata. 
Bulla diaphana, Gou.pv; Proceed. Boston Soc. Nat. Hist., im. 91. 
March 1849. 
ANIMAL of a delicate grass-green colour, everywhere minutely dotted 
with black and cinereous, except the side of the mantle next the shell, 
which is nearly white. The head is moderately convex, oblong, 
the part behind the auricles entire, not bilobed, destitute of any 
lobular appendages; eyes nearly central and approximate. Mantle 
large, nearly concealing the whole shell when the animal is expanded, 
and never wholly withdrawn. Foot oval, rather broader posteriorly 
than in front, where it is separated from the head by a broad and deep 
fissure. The average length, when crawling, was about one and a 
half inches. 
SHELL very thin, nearly colourless, finely and closely striated all 
over its surface, quite ventricose, resembling in its general features 
B. fusca and B. elegans. [3.P.c.] 
Length about three-fourths of an inch. 
Drawn up in shrimp-nets near the mouth of the harbour of Rio de 
Janeiro. 
Figures 265, 265 a, 265 b, three views of the animal, with the shell : 
265, front of the animal in outline ; 265d, the shell. 
