158 Mr Lake, Skell-depu'sits foniied bij the 



means rare. Mr C. E. Gray, of the Sedgwick Museum, went down 

 shortly after my first visit, and in a very short time obtained most 

 of the following species, but a few names have been added to the 

 list from specimens collected subsequently : 



Sphaerium corneum (L.), 

 Bithynia tentaculata (L.), 

 Vivipara contecta (Millet), 

 Valvata piscinalis (Miiller), 

 Limnaea stagnalis (L.), 



„ peregra (Mtiller), 



„ auricularia (L.), 

 Pkuiorhis corneus (L.), 



„ umbilicatus Miiller, 



„ caiinatits Miiller, 



„ vortex (L.), 



„ contortus (L.), 



Pliysa fontinalis (L.), 

 Helix nemoralis L., 

 Theba cantiana (Mont.), 

 Hygromia striolata (Pfr.), 

 Vitrea draparnaldi (Beck), 

 „ cellaria (Miiller). 



Even now the list is probably far from complete, and a closer 

 examination would no doubt reveal the presence of many other 

 forms. 



The last five species are land-shells, and, with the exception of 

 Vitrea cellaria, they occurred in Mr Gray's first collection and were 

 identified by Mr Hugh Watson. Vitrea draparnaldi does not 

 appear to be a native of the county, but is found in and near green- 

 houses ; for instance, in the Botanical Gardens. In Mr Gray's first 

 collection, which was made below the railway-bridge, it was repre- 

 sented only by a single specimen, which we supposed to have come 

 from the florist's greenhouses close by. But at a later date he 

 found it to occur abundantly at the beginning of the tow-j)ath, 

 some five or six hundred yards above the greenhouses. In order 

 to make sure that the specimens really belong to this species they 

 were sent to Mr Watson, who agreed with the identification. 



Since there were so many specimens of Vitrea draparnaldi at 

 the beginning of the tow-path, and so few (at least comparatively) 

 below the railway-bridge, it seems clear that they cannot have been 

 carried far, for otherwise they would have been more evenly dis- 

 tributed. It is most probable indeed that there was a colony of this 

 species in the immediate neighbourhood. The nearest greenhouse 

 that I have been able to find above the locality where the species 

 was so abundant is five or six hundred yards off, and stands well 



I 



