The Scottish Naturalist. 207 



P. carinatus Mull. — Pond in Royal Botanic Garden, Edin- 

 burgh, into which it has been perhaps introduced. 



P. complanatus L. — " Lochend, Edinburgh" (Haddin in 

 Trans. Glasgow Nat. Hist. Soc. 1. 251). 



P. vortex L. — In shallow slow running streams and stagnant 

 water. Widely diffused but not I think common. It occurs 

 near Perth in several places, Aberdeen, Kirkcudbrightshire, &c. 



P. spirorbis L. — In similar localities, and of like distribution 

 as the last, which it very much resembles. I have not met 

 with it. 



P. contortus L. — This, though rather local, is in my experi- 

 ence certainly the most abundant species of Planorbis in Scot- 

 land. It inhabits weedy muddy ponds, ditches and marshes. 

 The var. alba is reported from Lerwick. 



P. nitidus Mull. — In ponds and streams, widely distributed 

 but local. I find a good way to procure shells of this and 

 other small aquatic species, is to take a tin canister full of the 

 mud and decaying plants among which it is found, and on 

 reaching some, turn the contents of the canister into a large 

 basin full of water, and put a piece of muslin over the basin, 

 touching the water ; for several days afterwards the molluscs 

 will be found adhering to the muslin. 



Physa fontinalis L. — A common species in weedy ponds and 

 ditches. The var. curta is the only form that occurs in Perth- 

 shire, or indeed that I have found anywhere in Scotland. It 

 attains an elevation of at least 1000 feet. 



P. hypnorum L.— This is a much rarer shell than the last, 

 though said to occur throughout. I have not found it myself, 

 but have seen a Perthshire specimen taken by Mr. James 

 M'Farlane. It inhabits ponds and ditches, and may sometimes 

 be found out of the water. 



Limima pcregra Mull. — The commonest and most widely 

 diffused of all the fresh water mollusca, inhabiting rivers, ponds, 

 ditches, and marshes in every locality. I have found it at an 

 altitude of 1 700 feet. This species is subject to much variation : 

 the following varieties occur : — Burnetii in " Loch Skene, Dum- 

 fries-shire;" lacustris in mountain lakes and lower localities, as 

 Barean Loch, Colvend, Kirkcudbrightshire ; ovata in ponds, 

 lakes, and canals, attaining a large size ; labiosa, " Appin in 

 Argyle;" picta, "Alva in the Hebrides;" decollata in a cold 

 spring, Glenalmond, Perthshire ; intermedia, Ross-shire ; oblo/tga, 

 Largo, Fife ; sinistrorsa, near Dalmarnoch Bridge on the Clyde. 



