474 THE ZOOLOGIST. 
foot-marks. In other places I noticed them lying on the mud. 
Some full-grown ones were one inch and a quarter in diameter. 
At Askern this species is found both in a living and a sub- 
fossil state. 
P. contortus, Linn. Contorted Coil Shell.—Frequent in ponds 
and drains near Castleford. 
Var. albida.—‘‘ Three specimens from a pond at Castleford, 
1869.”—J. Wilcock, in MS. 
Physa hypnorum, Linn.—Ponds and ditches near Castleford, 
often swum together in hundreds, dead. ‘‘ Of the carnivorous 
propensities of this species I have had several proofs. In 1865 
I put a few into an aquarium to observe their habits. In a few 
days afterwards I noticed four sticklebacks lying at the bottom 
of the tank, and several mollusks upon them. ‘The body of the 
fish was eaten and the head and tail left. About a week after, 
other sticklebacks were devoured, but I could not ascertain 
whether they had been killed by the mollusks or not.”— 
J. Wilcock, in MS. 
P. fontinalis, Linn. Stream Bubble Shell.—Plentiful near 
Castleford, and at other places. 
Var. inflata.—River Went. 
Var. oblonga.—River Went. ‘‘ In 1868 one part of the river 
about ten yards in length swarmed with this variety, intermixed 
with a few of the variety inflata. Ihave not observed them in 
such profusion since.”—J. Wilcock. 
Limnea peregra, Mull. Wandering Mud Snail.—Abundant. 
Var. ovata.—One of the commonest varieties. 
Var. acuminata.—Ditches at Ackworth. 
Var. oblonga.—Canal at Knottingley. 
Var. labiosa.—Whitwood and Castleford. 
L. auricularia, Linn. Ear-shaped Mud Shell.— River Went, 
and disused quarry at Hillam. 
L. stagnalis, Linn. Lake Mud Shell.—Abundant at Castle- 
ford. Specimens occur in ponds which have the last whorl very 
much enlarged and somewhat square in form. 
Var. /ragilis.—This form, which some conchologists consider a 
distinct species, is common in the Castleford drains. It is some- 
what difficult to distinguish when associated with immature 
specimens of the type. In May of this year I observed several 
thousands of this variety with young of the type in a narrow 
