276 THE SCOTTISH NATURALIST 



A pond at the brick depot near the Bridge of Don, Aberdeen, 

 yielded Planorbis crista, also Limncea peregra and Pisidia. 



Limna>a truncatula was nowhere common, though generally 

 distributed in ditches and wet places, and was collected in every 

 locality visited, along with Pisidia, which could be found in every 

 pond, ditch, stream, or boggy ground. 



I did not see Physa fontinalis, which Mr Simpson says occurs 

 commonly in most places on the sloping banks near the Bridge of 

 lion. He also says that Physa acuta formerly occurred very 

 commonly in a mill pool in connection with the Banner Mills, 

 Aberdeen. 



I did not see any species of Sphicrium, which may easily be 

 accounted for by my not happening to visit (in the very limited 

 time at my disposal) suitable places in which species of this genus 

 might occur. 



My use of the terms abundant, very common, common, etc., is 

 only relative as regards the area of this investigation, and intended 

 to convey the idea of differences in point of number of specimens 

 in the various localities examined. It has no reference to any other 

 part of the kingdom. A species alluded to in these notes as 

 abundant might only be common in comparison with abundance 

 as understood in England. 



It will be appropriate to supplement my own observations 

 by notes which Mr James Simpson of Aberdeen has supplied 

 me, in reference to the records made by William L Macgillivray 

 and Robert Dawson, many years ago. He states that many 

 of the habitats mentioned by these two writers are either 

 obsolete, or greatly changed since their time. 



In regard to the sandhills so often mentioned north of 

 Aberdeen their appearance has been completely changed. 

 Though golf links in Macgillivray's day, they have in more 

 recent years been kept in better golfing condition than 

 previously. Formerly there existed dense patches of gorse, 

 broom, and other vegetation which was very productive of 

 mollusca in great variety ; but this has now all been cleared 

 away and the grass kept short, and numerous ponds, ditches, 

 and marshy ground which yielded numerous fresh-water 

 species have been either drained away or filled up. These 

 same remarks apply more or less to the succession of 

 golf links throughout the sandhills up the coast-line of 

 Aberdeenshire. 



