82 
came frotu Ronneby, Sweden, belonged to P. obtusale, I have some 
doubt as to whether the original specimens of C1 e s s i n s parvulum 
belong to that characteristic form which Woodward and I myself 
have mentioned under that name. 
Pisidium parvulum B. B. AVoodward is the smallest Pisidium 
found in Denmark and the smallest one dealt with in AVoodward’s 
Monograph. It has some resemblance with young ones of P. supinum 
A. Schmidt, but its outline is more squarish. By the ridges 
mentioned above and by its characteristic hinge (figured by AV o o d- 
ard) it differs essentially from all other Danish and Scandinavian, 
Pisidiums. 
w P. parvulum B. B. AV oodward was found by me in the Danish 
lake Fursøen in 1898 and mentioned in my paper „Bidrag til 
vore Ferskvandsmolluskers Biologi“ (Vid. Medd. Naturh. Foren. 
Kjøbenhavn 1899) as P. parvulum Clessin. 
It has been found later on by H. Lynge, in Ladegaardsaa 
Damhussø and Farum Sø, Sealand 5 and by Teilman-Friis 
in Hastrup Sø in AVest Jutland, and AVoodward records 
it now from Lake Baikal. 
A peculiar triangular thick-shelled Pisidium was found 
some years ago in Sjæl Sø, Sealand, by H. Lynge and was 
determined by AV e s t e r 1 u n d as Pisidium supinum A. Schmidt. 
I found later on a corresponding form in the Fursø, Sealand, and 
in Grenaa Aa, Jutland, and followiug AVesterlund I referred 
all these to P. supinum Schmidt. AVoodward has now referred this 
form to P. casertanum as a variety, and I must admit that he is right. 
From this it follows that the real P. supinum A. Schmidt is now 
only known from one locality in Denmark, viz. from Sk ar ri tsø, 
Sealand, where H. Lynge has found a few specimens. 
In Denmark we have the following species of Pisidium : 
Pisidium amnicum, Muller: in all parts of the country 
— astartoides, Sandberger; only from the Pleistocene: Sea¬ 
land, Funen 
