210 PROCEEDINGS OF THE MALACOLOGICAL SOCIETY. 



Specimens received from the Continent under tMs name are mostly 

 flattened forms of casertanum, which is hardly consonant with the 

 " tumidiuscula " of Philippi's description. In the absence of the 

 type, and considering the doubt attaching to its identification, it 

 will be wiser, for the present at all events, not to adopt the name. 

 As regards the Pisidium cinereum of Alder,'' we are furnished with 

 a description, which, though far ampler than those of the species 

 just passed in review, still leaves much to be desired for the purposes 

 of modern requirements. On the other hand. Alder's types are 

 extant in the Newcastle Museum, and from these and the numerous 

 co-types distributed by him to correspondents, the identity of his 

 species is well established, so that we are on sure ground, and hence 

 it would be safest in my judgment to employ his name in future 

 for the species, 



Pisidium parvulum (Clessin MS.) Westerlund. 



This species was established by Westerlund on Clessin's manuscript 

 in 1873,® with a very imperfect description, and no figure. A variety, 

 martensi, CI., was also indicated. The habitat being given as 

 Blekinge district, near Ronneby. The species was repeated by 

 Clessin in his monograph on the " Cycladeen " and figured.^ 



Whilst preparing the " Catalogue of the British Species of 

 Pisidium ", I received from Dr. A. C. Johansen examples of a Danish 

 form under the above name, and, although it had not then been found 

 in Britain, included it, with illustrations, in the " Catalogue " as 

 a species to be looked for, but did not so completely describe it as 

 I should have done had it been British. The occurrence of the 

 same form in Lake Baikal was also noted, whence it had been 

 received under the name " P. aliena, Mts." — a name which cannot 

 be traced, and which has certainly nothing to do with the P. alienum 

 of Clessin/" which is a synonym for P. amnicum, var. 7iova, Paul. 



In 1914 Dr. Johansen in a " Note on the Danish species of 

 Pisidium ",'^ pointed out that this Danish form was apparently 

 not the parvuhim, Clessin, of Westerlund, but distinct. He further 

 mentioned that some co-types from Ronneby, determined by 

 Westerlund, belonged to P. ohtusale. 



For reasons which will presently become apparent, it seemed 

 desirable to probe this question now, and accordingly endeavours 

 were made to see or ascertain the identity of authenticated specimens. 

 Dr. Scharff of the National Museum of Ireland very kindly allowed 

 me to inspect specimens under his charge that comprised two sets 

 from Ronneby, the one received directly, the other indirectly from 



■^ Trans. Nat. Hist. Soc. Northumberland, ii, 1838, p. 341. 



8 Fauna Moll. Svecite, ii, p. 553. 



9 Syst. Conch. -Cab., eel. Kiister, 1874, p. 17, pi. i, f. 17-21. 

 1° lb., p. 269, 1879. 



" Vidensk. Meddel. Dansk. Naturh. Foren., Ixvi, pp. 81-3. 



