MOLLUSCA IN THE NEIGHBOURHOOD OF PONTEFRACT. 475 
dyke in a grass-field near Castleford; in fact, the bottom of the 
dyke was paved with them, but there were no adults of the type, 
except one or two dead ones. ‘The shells are often slightly 
covered with Conferve, but when cleaned they appear of a very 
fine and somewhat ruddy horn-colour. Apropos of cleaning, I 
may remark that some care is necessary, otherwise the thin edge 
of the mouth will become chipped. I usually soak them nine 
or ten hours in soap and warm water, with a little soda, and 
then brush them well with a hard tooth-brush, keeping the brush 
well soaped. 
L. palustris, Mull. Marsh Mud Shell.—Near Methley, and 
near Milford. I have not seen it anywhere nearer to Pontefract. 
Although described in books as common, it is not so in this 
district. 
L. truncatula, Mull. Small Mud Shell. — Frequent, but 
less so than formerly. Ihave often rambled a whole day without 
seeing one. 
Var. major.—Castleford. 
Var. elegans.—Methley. 
L. glabra, Mull. Elongated Mud Shell.—Near Castleford, 
and near Ackworth. 
Var. elongata.—Castleford, in company with Physa hypnorum. 
Ancylus fluviatilis, Mull. River Limpet.—River Went, and 
near Brotherton. 
Var. capuloides.—Wentbridge and Ackworth. ‘‘ In 1864 the 
stones at the bottom of the shallow places in the Went were one 
compact mass of this variety, but a strong flood in the autumn 
swept nearly all the stones and shells away. Light horn- 
coloured specimens often occur, which might easily be mistaken 
for the variety albida.”—2J. Wilcock. 
L. lacustris, Linn. Oblong Limpet.—In Lord Houghton’s 
fish-ponds at Fryston; also at Castleford and Ferrybridge. 
Var. albida.—In the River Went, on leaves of the water- 
lily ; rare. 
(Lo be continued.) 
