Quarterly Journal of Conchology . 25 



common species, in size, form, and consistency, are very perplexing to 

 the Concliologist. Specimens found at Eedhengh and on Holy Island 

 have rather a strong shell and the spire much produced, vphilst some 

 from the locality of Darlington possess the opposite extreme, and have 

 a very thin, delicate shell, and scarcely any spire. The latter comes 

 very near to the form got by Mr. Thompson in Lough Neagh, Ireland, 

 which is the Gulnaria lacustris of Leach. 



Limnsea auricularia Linne. — Rather rare in the district ; is to he 

 Inet with at Gosforth Lake, in Northumberland, and in ponds near 

 Darlington, county of Durham. 



Limnsea palustris Muller. — Not common. Those found in marshes 

 and still water in the district grow to a large size, but at the margins 

 of rivers they are much stunted in growth, and have the aspect of a 

 distinct species. On the shores of the Tyne, where they are more 

 abundant, they are not larger than the common-sized L. trnncatula, 

 and might be taken for that species but for the less ventricose whorls, 

 and that the latter species is also found in the same situations in an 

 equally dwarfed condition. 



Limnsea trunculata Muller. — Common in ponds and ditches 

 throughout the district. Occurs in a pond near Kenton, and at 

 Whitley reservoir, near Cullercoats, where the specimens are good 

 and well defined. 



Limnsea glabra Muller. — In ponds and ditches ; not uncommon 

 near Newcastle. 



Ancylus fluviatilis Muller. — Of frequent occurrence throughout 

 the district. Is met with in the rivulet in Scotswood Dean, stream 

 near Brockley Whins, the river Coquet at Kothbury, and sundry 

 other places. 



Ancylus lacustris Linne. — Rather rare, on aquatic plants in ponds 

 and ditches. Occurs in ponds near Ben well and Crag Lake, North- 

 imiberland ; at near Middleton One Row, in the county of Durham. 



Arion ater Linne (common black slug). — In fields, woods, and 

 hedges very common. Ferussac considers the black head and ten- 

 tacles, and the transverse black lines round the margin of the foot, to 

 be the only permanent distinctive characters in this very variable 

 species. The varieties occurring in this neighbourhood are the 

 following : — ■ 



1. Entirely black. 



2. Black, with the sides of the foot yellow or orange. 



3. Blackish above, with a black band on each side of the body, and 



the sides yellowish white. 



4. Yellowish or greenish white, with black tentacles. The young 



are always much paler than the adults, and are sometimes of 

 a transparent white. The Rufous variety is not met with in 

 this district. 



Arion flavus Ferussac. — Occasionally found on the moors near 

 Haltwhistle, in Northumberland. M. Bouchard- Chan tereaux considers 

 this species distinct from A. ater, and it has not the characters of the 



