76 NELSON AND TAYLOR : ON YORKSHIRE MOLLUSCA. 



Limnaea peregra Miill. 



Widely distributed and very abundant. 



This species, as understood in England 

 has received a multitude of specific and 

 varietal names, as the result of the labours 

 of the different British and Continental 

 conchologists who have studied it. Even 

 by the more conservative of the foreign scientists several forms 

 are recognized as perfectly distinct species which we in England 

 consider varieties only. The wide range of variation of this 

 species makes it quite necessary that some classification of its 

 varied forms should be adopted, and we shall therefore in the 

 present catalogue accept the varieties instituted by Dr. Jeffreys, 

 and add such other well-marked forms as may seem to us 

 sufficiently distinct to be noticed. 



L. peregra is one of the most widely distributed species 

 known, and has been reported from every European country, 

 large tracts of Asia, Africa, and America, and even from Tas- 

 mania. It is found over the whole of the British Isles and is 

 widely distributed throughout Yorkshire, being recorded from all 

 of the twenty-five districts into which we have divided the county. 



It can sustain the greatest extremes of temperature, and 

 has been found living in water at Burnley which at times 

 attains a temperature of loo" Fahr., as we are assured by Mr. 

 Wigglesworth, while in the opposite direction it is found to exist 

 in the icy waters of the greatly elevated Pyrenean lakes. 



This species is found in the brackish water of the Baltic, 

 attached to sea-weeds, &c., up to a depth of twelve fathoms; 

 but in these situations the shells are much dwarfed, owing to 

 the unfavourable conditions under which they exist. In the 

 brackish-water lakes in the Landes, where it is also found, the 

 specimens are very often deformed, owing to interruptions of 

 the regular growth. 



Trans. Y.N.LT., 1890 (pub. 1891). Series C 



