34 NELSON AND TAYLOR : ON YORKSHIRE MOLLUSCA. 



lying alluvial plains of the three river systems : the Ouse and 

 its tributaries in the centre, the Tees in the north, and the Hull 

 in the south-east. 



It is found in great abundance in a subfossil state in 

 the mud cliffs at Hornsea, and is thrown up by the moles 

 in the neighbourhood of Askern, testifying to its former 

 occurrence in those places. 



The egg capsules of this species are very peculiar, re- 

 sembling small curved spines projecting perpendicularly from 

 the leaf upon which they rest. The number of eggs in each 

 capsule is variable, but a greater number than eight has not 

 been noticed. They are arranged in a single series, and are of 

 a reddish colour. 



3. Vale of York — Generally distributed in ponds in the Ainsty, F. G. 



Binnie ; pond at Church Fenton, J.D. ! pond near Healaugh 

 Hall, Tadcaster, F. G. Binnie ; in profusion in Askham Bog, 

 and greatly on the increase there, W. C. Hey I pretty common 

 in the River Foss and the small stream running into it, F.M.C. ; 

 a few in the River Ouse drift, R.M.C. ; one at South Milford, 

 in 1879 ! Boston Spa, J. Emmet. 



4. Humber — Canal near Burton Hall ! ditch at Barlow Common, Selby ! 



abundant, but very thickly encrusted, amongst decaying vegetation 

 in a ditch near to and in the canal at Selby ! 



7. Went Vale — A few in the River Went, attached to a caddis case, C. A. ; 

 a few on caddis cases in Went dyke, 1865, between Ackworth and 

 Went Bridge, J.W. ; Askern, H.S. ! Ackworth School Canal, but 

 not found in such numbers since it was cleaned out ; empty shells 

 formerly found in mud turned out of mill stream in 1879, H. 

 Richardson ; Campsall Park, L.P. ; large numbers in dykes on 

 both sides of the road between Smeatonand Campsall, J.W. 



20. LoLuer Tees — In ditches at Great Ayton, J. W. Watson. Seems to be 

 of rare occurrence in this district ; I have taken one or two speci- 

 mens at odd times in the fish pond at Kirkleatham near Redcar, 

 and Mr. J. W. Watson informs me it used to be common in many 

 of the ponds near Gt. Ayton. I however have not been able to 

 confirm this up to the present time. — Baker Hudson. 



22. Upper Derwent — It appears in the late Mr. Bean's list of Scarborough 



shells : not found by Mr. J. H. Ashford. 



23. Chalk Wolds — Leckonfield Moat, J.D.B. ; Bridlington, common 



attached to caddis cases in a pond near railway on west side of 

 line to Scarborough, April 12, 18S4, G. Wingate! 



Trans. Y.N .U., 1883 (pub. 1885). Series C 



