312 



G. ROBERTS I MOLLUSCA OF WRESSLE. 



Planorbis complanatus. Common in most drains. 



Planorbis corneus. In a small pond near the Castle, and in the 

 Fleetdyke. Also in a small pond near the Crescent Inn going to 

 Bubwith. Here Beanland threw in his net and brought out at 

 the first haul a very fine one amongst a lot of Zannichellia 

 paliistrisy but none were found afterwards. 



Planorbis contortus. White Rails dyke, J.B. 



Physa hypnorum. In a moist muddy dyke, mostly lying on the 

 surface — dead and empty shells. 



Physa fontinalis. Fleetdyke, hundreds on June 12th, 1886, but 

 very few to be found July 24th. 



Limn sea peregra. Common in Fleetdyke and other places on July 

 24th, but nearly all young. It is curious what becomes of the 

 full-grown mollusks. Probably water-rats and shrews will feed 

 on them, and they may be able to extract the animal without 

 gnawing the shell. In the tidal drains such as the Fleetdyke, 

 mollusks may be more uncertain and unstable than in other 

 places not influenced by the tide, as by simply leaving hold of 

 their food-plant they may be floated either up or down to a 

 considerable distance every day. Dead shells .will be floated 

 down into the river and forwards into the sea in vast numbers. 

 I once found shells of Spharium comeum, Sphcerium rivicola, 

 Neritina fluviatilis, Bythinia tentaculata, Valvata piscinalis, 

 Limncea peregra, Limncea truncatula, Succinea elegans, Helix 

 rufescens, Helix caritiana, Helix hispida, Patella vulgaris, Litto- 

 rina rudis, and Littorina littorea, with the tooth of a rat and the 

 tooth of a dog, in a barrowful of sand which had been dredged 

 from the river Aire. The epidermis on many of these was quite 

 perfect. 



Limnaea peregra var. ovata. Newsholme, 1885, J.B. 



Limnaea auricularia. Newsholme, rare, 1886, J.B. 



Limnaea stagnalis. Newsholme, 1886, J.B. A small form like 



fragilis was in the Fleetdyke in 1884. 

 Limnaea palustris. Type and varieties tincta and elongata in new 



drains at Newsholme, July 1886, J.B. 

 Limnaea truncatula. In White Rails drain, Newsholme, 1886, J.B. ; 



and on caddis cases in Fleetdyke. 



TERRESTRIAL. 



Arion ater. On the banks of the Derwent, 1886. 



Limax agrestis. Creeping on the reeds on the bank of the Derwent. 



Succinea putris. Common on mud near the Fleet. 



Naturalist, 



