128 HULL SCIENTIFIC AND FIELD NATURALISTS' CLUB. 



LimncBO. glutitwsa, and Paludestrina jenkinsi have not been 

 found in the other two divisions. The scarcity of Planorbis 

 vortex and abundance of P. spirorbis is a marked feature, 

 and a similar contrast is seen between P. fontanus and 

 P. nautileus. P. umbilicatus is very common, and all grada- 

 tions between this and P. carinatus may be found. If the 

 determination of P. parvus is correct, it is the only species 

 found in the lacustrine deposits which does not exist in the East 

 Riding - at the present time. Limncea auricularia, L. stagnalis, 

 and L. palustris are local. Both limpets are uncommon, 

 Ancylus being found on the west only, while Velletia occurs 

 also sporadically on the east ; only one of the localities 

 recorded for Neritina is east of the Hull. As indicated 

 above, Unio is rare. Dreissensia has not been found in the 

 Hull docks or timber ponds, where the water is salt except in 

 the new Alexandra Dock. Conchology seems to have been 

 neglected by the earlier Hull naturalists : a small collection 

 made by George Norman, now in the Hull Museum, contains 

 land, freshwater, and marine shells, British and Foreign, 

 without names or localities. Mr. J. D. Butterell's lists for 

 Hull, Hornsea, and Beverley (1879-1883) form the foundation 

 of our knowledge of the mollusca of this area, and his thorough 

 investigation of the valley of the River Hull has afforded a 

 sufficient reason for the absence of detailed lists by later 

 workers. Mr. L. B. Ross is responsible for man) - records in 

 the neighbourhood of Driffield, but has not published a full 

 list ; and the work of Mr. F. W. Fierke, whose knowledge 

 of the Hull district is unrivalled, is represented by brief notes 

 only. 



With the exception of a small area in the neighbourhood 

 of Brandesburton, the whole of this district has been well 

 investigated, and for this reason the smaller land species 

 appear as numerous as in the central division. Helix 

 horte>isis, H. arbustorum, H. rufescens are rare or local, and 

 H. granulata is not known. The small plantations of 

 Holderness yield better results in the winter months than in 

 the summer, H. aculeata, H. pygmcea, Vertigo edentula, Papa 

 umbilicata, &c. , being then more easily found, but they are 

 not rich in woodland species, probably because all are of 

 recent growth. There is no record of Clausilia, and Balea 

 has only been found in small numbers on trees in hedgerows; 

 these are, however, the only East Riding stations for this 

 species. On the coast, H. virgata and H. caperata abound, 

 but H. itala occurs more frequently on the gravels inland, 

 approaching the coast only at Hornsea. 



