NATURAL HISTORY SOCIETY OF GLASGOW. 173 



notice at the time than consigning them to a pill-box, with the 

 name of the locaHty and the conditions under which they were 

 found, till an opportunity might occur for closer inspection and 

 arrangement. 



The first shell is the little bivalve Pisidium fontinale, var. 

 Hensloivana, taken in the Glasgow and Paisley canal. It is the 

 Pisidium Hensloivana of Shepard. It was first discovered by Prof. 

 Henslow in the River Cam, near Cambridge, and occurs in many 

 of the northern, eastern, and south-western counties of England, 

 as well as in South Wales and in Cork, but it has not hitherto 

 been discovered in Scotland. It is not an uncommon thing for 

 such small shells to be overlooked by being mistaken for closely 

 allied species, but in this case the most cursory inspection would 

 discover the remarkable little elevated plate on each valve near 

 the umbo, which at once distinguishes it from all its congeners. 



The second shell is Planorhis comjjlanakis; it is found moderately 

 common in Lochend Loch, Edinburgh. Jeffreys says: "It inhabits 

 marshes, ponds, canals, ditches, and standing water everywhere 

 in England, Wales, and Ireland, but I am not aware of any Scotch 

 locality." 



This shell is readily distinguished from its nearest ally Planorhis 

 carinatus, by the keel being placed below instead of in, or towards 

 the middle of, the periphery. It is somewhat singular that while 

 this shell is so plentiful all over England, Wales, and Ireland, 

 the small patch of water near Edinburgh, known as Lochend 

 Loch, is its only known locality in Scotland. There is another 

 remarkable circumstance connected with this loch. Some few 

 years ago Mr James Bennie of the Geological Survey of Scotland 

 sent me some mud from it, for the purpose of examination for 

 Ostracoda. Amongst others, a few valves were found of a species, 

 Gonioctjpris mitra, which Prof. G. S. Brady and I discovered in 

 the fens of Norfolk, which are rather of a brackish character, and 

 we could detect it nowhere else, leading us to think that the 

 species was peculiar to that flat district; we were therefore surprised 

 to find it in this distant isolated fresh-water loch. Further search 

 was made for living examples, but although dead valves were com- 

 mon, the li\dng animal was not met with. The same may be said of 

 of Planorhis comj^lanatus, which probably arises from the fact that 

 the loch is being filled up through the emptying of the town 



