166 THE ZOOLOGIST. 
Planorbis spinorbis. The Round-spired Coil-shell.—In clear 
springs and springy ditches. Less abundant than the last. 
Planorbis contortus. The Twisted Coil-shell.—In the ditches 
of all the Sussex rivers, and occasionally in very weedy ponds. 
Planorbis fontanus. The Shining Coil-shell.—Sparingly in clear 
water, at Cowfold and Henfield, amongst Callitriche verna (B), 
and in the Mill-stream at Ratham (J). 
Planorbis nitidus. The Streaked Coil-shell.—In a ditch near 
the ruins of the Priory at Lewes, and in a pond at Old Deane 
Farm, Henfield.—B. Mr. Unwin has met with it in a ditch in 
Kingston brooks, near Lewes, adhering to Conferve. He has 
found it a good plan to drag out a quantity of the Conferve, and 
on reaching home to place it in a basin and pour warm water 
upon it. The animals at once relinquish their hold and fall to 
the bottom, when they may be easily collected. Mr. Borrer, in a 
recent letter, has pointed out that Segmentina lineata, Fleming, 
of Mr. Unwin’s list is referable to the present species, Planorbis 
nitidus Miiller, and not to Acme lineata, Draparnaud, as stated 
ante p. 126. It would seem, therefore, that Mr. Unwin has given 
the same species twice under different names. Mr. Weaver has 
seen specimens of this shell said to have been collected in the 
parish of Harting, but has not found it there himself. 
Physa fontinalis. The Stream Bubble-shell.—May be found in 
water-cress and other aquatic plants in streams and canals, and is 
everywhere tolerably common. It occurs’ in most of the ditches 
of the before-mentioned levels. 
Physa hypnorum. The Slender Bubble-shell.—Is rather more 
local, affecting ponds, ditches, and rank grass in dried-up pools. Mr, 
W. Jeffery has noted it at Ratham, near Chichester, and at Lindfield. 
Both these species are gregarious, and may be recognized at once 
by the polished appearance of their shells, the surface of which, 
being more or less enveloped by an expansion of the mantle, is 
kept bright by the lubricating friction which it undergoes. The 
characters by which fontinalis may be distinguished from hyp- 
norum are the oval instead of oblong shell, larger and wider mouth, 
smaller number of whorls (that is, four or five, instead of six or 
seven), shorter spire, and deeper suture. The foot of the animal 
in fontinalis is rounded in front instead of lanceolate, and the body 
is of a uniform greyish colour, instead of being minutely speckled 
as in hypnorum. Gray considered these two generically distinct, 
