FRESH-WATER SHELLS. II 



Mr. Fierke states, are scattered about the district, but 

 are usually unproductive. 



Pond at Tothby^ Lincolnshire ^ dug in 1 87 1. — Particulars 

 communicated by Mr. J. E. Mason and Mr. J. B. Davy. 

 Of special interest from the fact that the date of excava- 

 tion is known. Situate on the clay near the foot of the 

 Wold, in the corner of an arable field (T. C.Johnson's) 

 at Tothby, on the borders of the parishes of Alford and 

 Rigsby, and said to be quite isolated from other water. 

 Two small fence-ditches, sometimes containing a little 

 water received from the under-drains, open upon the 

 pond ; but Mr. Mason, in whose knowledge of the 

 locality I have the utmost confidence, expresses the 

 opinion that it is in the highest degree improbable, next 

 to impossible, that a flood should have caused a com- 

 munication with any other pond or water-course. Of 

 the plants, none are of kinds likely to have been 

 intentionally introduced ; duckweed and two Potanioge- 

 tons are conspicuous. Both the common newts occur, 

 and water-bugs and beetles abound, but Mr. Mason has 

 not seen a fish of any kind, although the nearest ponds 

 are well stocked with sticklebacks. Of molluscs, 

 Mr. Davy, in 189 1, obtained two species, Limncea 

 peregra and Sphcerium lacustre^ both in fair plenty. 

 The presence of the former, which, it is said, is generally 

 the first to appear in newly-formed ponds,^ is of no 

 special interest, but the establishment of a bivalve-shell 



^ See G. Roberts, " Topography and Nat. Hist, of Lofthouse," 

 18S2, p. 167. 



