NELSON AND TAYLOR : ON YORKSHIRE MOLLUSCA. 73 



20. Lower Tees — General in district, J. W. Watson ; Coatham Marshes, 

 grassy ditch by the old railway, small but deeply coloured, C. 

 Ashford, Journ. Conch., vol. ii., p. 236, 1879; plentiful in ditches, 

 Kirkleatham Road, Coatham, May 1st, 1887, Baker Hudson ! 



22. Upper Derwent — Scarborough, W. Bean, Theakston's ' Guide to Scar- 

 borough,' edition 10, p. 177, 1S71 ! Scarborough, C. Ashford, 1885! 



24. Holderness — Rejectamenta of Beverley Beck, CherryTree Lane, Kitchen 

 Lane, and Commonbank Nook, near Beverley, not common, 

 J.D.B., Journ. Conch., vol. iii, p. 293 ; Figham, May 29th, 1882, 

 W.D.R. ! plentiful in the River Hull at Driffield, L. B. Ross, 

 1882! Anlaby Road and Beverley Road, Hull, J.D.B., Nat., vol. 

 iv, p. 71, Dec, 1878; Bridlington, Rev.W. C. Hey, Journ. Conch., 

 ii, p. 312, Oct. 1879. 



Var. major Charp. 



3. Vale of York — Pond at Bishopthorpc, R. M. Christy, Zool., p. 183. 

 May, 1888. 



Monst. decollatum Nelson. 

 7. V/ent Vale — Ditch at Hessle near Ackworth! 



Genus LIMN.-EA Bruguiere. 



As Haldeman points out, Limnasa may be separated from 

 Physa by its dextral spire, and from Succinea by the fold upon 

 the columella which is wanting in that genus. 



Dr. Jeffreys remarks in his account of this group that lliey 

 frequent shallow and still waters, but though they usually do 

 this, some of our commonest species are found living at great 

 depths in the Swiss lakes, and in those situations are said to 

 respire water and not free air as is usually the case. 



The anatomical relations of Limn^ea are, according to 

 Professor A. G. Weatherby, rather with Limax than with their 

 undoubted allies, the Planorbes; and the foot gland, which is 

 found in some Limnsese, is stated by Sarasin to be the homo- 

 logue of the byssal gland of the bivalves. 



This genus is found fossil in the Oolite and in subsccjuenl 

 deposits ; in the Eocene of the Isle of Wiglit it occurs in 



