BOYCOTT : THE HABITATS OF FRESHWATER MOLLUSCA. 



243 





River 



Streams 



Lakes 



Running 

 ponds 



Closed 

 ponds 



Number of habitats > 

 in each group - ) 



I 



6 



2 



22 



86 (113) 



Lif/incea peregra 

 L. auricularia 



X 

 X 



6 



X 

 X 



20 



31 



L. palustris 

 L. stagnalis 



X 

 X 



I 

 I 



X 



3 



7 



2 



8 



Plarwrbis corneiis - 



X 



— 



— 



— 



— 



P. albus - 



X 



3 



X 



7 



13 



P. naiitikus 



— 



— 



— 



7 



40 



P. complanatus 

 P. vortex 



X 

 X 



I 



2 



— 



5 

 5 



5 

 3 



P. leucostojna - 



— 







X 



I 



4 



P. con tortus - 



X 



I 



— 



2 



— 



P. font amis 

 Ancylus fiiwiatilis - 

 A. laaistris 



X 

 X 

 X 



I 



— 



6 

 3 



13 



20 



Physa fontinalts 

 Bith. tentacnlata 



X 



X 



I 



— 



z 



- — 



B. leachii 



X 







— 



— 



— 



Valvata piscinalis - 



X 







— 



— 



— 



V. cristata 



X 







— 



— 



— 



Pahidestrina Jenkifisi 



— 







— 



I 



— 



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KJ ri'CU I'll tU f It //I 



Anodonta cygnea 



X 







X 



- — ■ 



— 



Sphcerium corneuni - 



X 



I 



— 



6 



17 



S. lacustre 



— 







— 



2 



16 



Pisidinm aniniaifu - 



X 







^ 







— 



P. casertanuvi 



— 



2 



X 



— 



3 



P. 7iitidum 



X 



2 



— 



I 



4 



P. personation 



— 



— 



— 



2 



4 



P. pusillum 



X 



I 



X 



— 



I 



P. militi77i 



X 







— 



3 



10 



P. ptilchellvm - 

 P. sul)truncati4?n 



X 

 X 



4 



— 



4 



4 



P. henslowa7iufn 



X 



— 



— 



— . 



— 



P. obtusale 



— 



I 



— 



I 



4 



one hand to the almost still backwaters on the other, since all the 

 species enumerated occur in one large gently flowing artificial fish- 

 pond. The streams are on the other hand clearly not homogeneous, 

 and their connection with various ponds, the lakes and one another 

 makes their total of species less significant. The lakes have yielded 

 but seven larger sorts and two Pisidia ; they are the least easy of loci 

 to examine, though in the present case search among the debris after 



