299 



LAND AND FRESHWATER MOLLUSCA IN THE 

 SCARBOROUGH DISTRICT. 



Iv J. A. IIARGREAVES. 



(Read before the Society, December glh, 19 



The district examined is situated within a radius of six miles from 

 Scarborough, and with one or two unimportant exceptions all the 

 records are included in that area, which is also entirely in Vice- 

 county 62. 



The geological structure is entirely Oolitic, ranging from the Lower 

 Oolites to the Upper. It is chiefly, however, in the Middle Oolites, 

 and the soil is generally calcareous, as the strata include Limestones 

 and Calcareous Sandstones. On the coast the rocks are, in districts, 

 covered with sand and Boulder Clay ; whilst the Carrs, which are flat 

 and intersected with ditches, are alluvial on the surface. 



The district is diversified, rising to a height of 500 feet above sea 

 level on Oliver's Mount, and 600 feet on Seamer Moor. There are 

 no valleys of importance except the well-known Forge Valley, which 

 is of post-glacial age, and cuts through the Middle Oolites. It is 

 extremely rich in molluscan life notwithstanding its small area. 



There are no canals, but the Derwent flows through Forge Valley, 

 and has an overflow stream to the sea near Scalby, whilst the River 

 Hertford drains the Carrs. Ponds are numerous. 



Rainclifife, Forge Valley, and Hackness are not only well wooded, 

 but contain an unusually large number of different kinds of trees, 

 and are equally prolific in the variety of the smaller forms of veget- 

 able life. 



The district was well and completely worked more than a genera- 

 tion ago by the great conchologist Bean, by Leckenby, and others. 

 Unfortunately the only records available are a list of names in 

 Theakston's " Guide to Scarborough." As this list includes such 

 species as Clausilia biplicata, Helix lapicida, Unto margaritifer, and 

 Paludina listeria none of which occurs within many miles of Scar- 

 borough, it is evident that Bean gave the name Scarborough a very 

 extended signification, and his list cannot be relied upon as an indi- 

 cation of what occurs in the immediate neighbourhood. Since that 

 time other workers have given short lists in various periodicals, for 

 instance, Mr. Miller Christy, Rev. W. C. Hey, and Mr. Chas. Ashford, 

 but, so far as I know, no approximately complete list has been made, 

 and the following has been compiled during the last few years. 



I am indebted to the Rev. AV. C. Hey for many records, particu- 

 larly in the western part of the district ; to Messrs. A. Harnian and 



