26 
bulla, dipper. 
what membranaceous, especially about the margin, with a 
single minute lateral volution which is a little prominent, 
transversely wrinkled, and covered with a silvery shin 
tinged with pink, changeable in different positions of light, 
and occasionally appearing nacred or with a metallic lus¬ 
tre : aperture extending over the whole shell: length 
nearly an inch and a half; breadth an inch. 
It much resembles B. Plumula, but is more membrana¬ 
ceous, rather more convex, with the volution more piomi- 
nent, and not placed so laterally. 
Found by Montagu, at the salt rock, in the estuary of 
Kingsbridge, Devon: rare. 
18. Bulla fontinalis. Stream Dipper. 
Lister , pi. 134. f. 34 —Da Costa, pi. 5. f. 6 —Dorset Cat 
pi. 21. f. 6— Linn . Trans, viii. pi. 4 f. 1. 
Shell oval, swelling, transparent, glossy, pale horn-color: 
spires four or five, rounded and well defined, reversed, wry 
little produced ; the first very large, the others small, obtuse 
at the point: aperture oval-oblong, reaching three-fourths 
of the length of the shell; the outer-lip reaching beyond 
the base Old ones are a little wrinkled longitudinally, with 
two or three faint“trans verse ridges on the body volution: 
length half an inch ; breadth a quarter. 
In stagnant and slow running waters, under the leaves 
and on the stalks of plants, v. v. 
. ID. Bulla rivalis. River Dipper . 
Linn. Trans, viii. pi. 4. f. 2. 
Shell oval-oblong, transparent, smooth, glossy, horn- 
color, with five or six reversed volutions ending in a very 
fine point: aperture oblong. It differs from B. fontinalis, 
in being more elongated and pointed, in having the 
volution not so proportionately large nor tumid, and in 
being more contracted at one end of the aperture; and 
from the next, in being of a more conic shape, and more 
sharply pointed : size of the last. 
Slow streams in Hampshire, and near Naas in Ireland: 
rare. v. v. 
20. Bulla Hypnorum. Slender Dipper. 
Lister , pi. 1059. f. 5—Walker, f. 54 —Lira. Tnmm. 
pi. 4. f. 3— Dorset Cat. pi. 18. f. 20. 
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