OF NORTHUMBERLAND AND DURHAM. 137 
4. L. evasra, JIZull. 
Limneus glaber, Gray, Turt. Man. 242, t. 9, f 106. 
Limneus elongatus, Drap. Hist. Moll. 53, t. 3, f 3, 4. 
In ditches and ponds, not uncommon near Newcastle. 
5. L. perecRrA, Will. 
Limneus pereger, Gray, Turt. Man. 233, t. 9, f 101. 
Var. Limneus ovatus, Drap. Hist. Moll. 50, t. 2, f. 30, 31. 
In ponds, ditches, and slow streams, very common. 
The numerous varieties of this common species, in form, size, 
and consistency, are very perplexing to the conchologist. We 
have got it with a rather strong shell, and the spire much pro- 
duced, at Redheugh and on Holy Island ; and a curious variety 
in the opposite extreme has been sent us from Darlington, by 
Mr. Wm. Backhouse, with a very thin delicate shell, and scarcely 
any spire. The latter comes very near to the form got by Mr. 
Thompson in Lough Neagh, which is the Gulnaria lacustris of 
Leach. 
6. L. auricunartra, Linn. 
Limneus auricularius, Gray, Turt. Man. 232, t. 9, f 100. 
At Prestwick Car (a small variety)—A.H. In ponds near , 
Darlington.—/r. W. Backhouse, from whom we have received 
very fine specimens. 
39. PH YSA, Draparnaud. 
1. P. rontinatis, Linn. 
Physa fontinalis, Gray, Turt. Man. 251, t. 9, f. 110. 
In ponds and ditches, not common. Preswick Car, Gosforth 
Lake, Mill Stream near Busy Cottage, Ryton, Marsden, and near 
Stockton. 
2. P. nypnorum, Linn. 
Aplexus hypnorum, Gray, Turt. Man. 255, t, 9, f. 113. 
In ditches and ponds, frequent. 
40. PLANORBIS, Miiller. 
1. P. cornzus, Linn. 
Planorbis corneus, Gray, Turt. Man. 258, t. 8, f. 95. 
In a pond in Mr. W. Backhouse’s grounds at Darlington. 
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