i8o The Irish Natiwalist. 



Pisidium ijulcliellum, Jenyns. 

 T. — — — — — — — IX — XL XII. 



This handsome species is generally distributed according to Thomp- 

 son (15), bnt I haye as yet only a few records. 



Foreign Distribution. — Great Britain, south Scandinavia, south Ger- 

 many, and France. 



Pisidium nitidiuni, Jenyns. 

 I. — III. — _ _ VII. VIII. IX. — — XII. 



This species occurs chiefly in ponds and lakes along the mountainous 

 districts of the west and north of Ireland. 



Fgrkign Distribution. — Great Britain, Iceland, Scandinavia, France, 

 and south Germany. 



Pisidium fontinale, C. Pfr. 

 I. — — — V. — VII. VIII. IX. — XI. XII. 



This very variable species probably includes Thompson's P. cinereum. It 

 is found in the mud of stagnant waters or slowly moving streams. 



Foreign Distribution. — Great Britain, Scandinavia, Austria, Swit- 

 zerland, Germany, France, Italy, vSicily, Spain, Algiers and Syria. 



Pisidium milium, Held. 



P. rosmui of Jeffreys is this species. It seems to have been overlooked 

 by Thompson, and is probably rare in Ireland. Miss Warren sent me 

 specimens from Co. Sligo. 



Foreign Distribution. — Great Britain, Scandinavia, Russia, Galicia, 

 Austria, Switzerland, Germ-any, France, Algiers, and Siberia. 



Pisidium. obtusale, C. Pfr. 

 — — — — — — VII. _ IX. — — XII. 



According to Thompson this is one of the rarest species in Ireland. It 

 has not yet been discovered in eastern or southern Ireland. 



Foreign Distribution. — North England, Scandinavia, Transylvania, 

 Germany, Switzerland and France. 



Pisidium pusillum, Gmel. 

 I. II. _ — V. — VII. VIII. IX. — — — 



This, the most common of the Irish Pisidia, is rarely met with any- 

 where, except in marshes. 



Foreign Distribution. — Great Britain, Iceland, south Scandinavia, 

 Russia, Transylvania, Switzerland, Germany. France, and Siberia. 



Genus— UNIO. 

 Unio margaritifer, L. 

 I. II. — IV. V. — — VIII. IX. X. XI. XII. 



This species differs anatomically so much from all other species of 

 Unio that many conchologists put it under a separate genus, Margaritana. 

 It is the only Irish species of the genus, and is found chiefly in the moun- 

 tainous districts, l-'rom this shell pearls have been obtained in great 

 quantity, especially in Tyrone antl Conneniara. 



Foreign Distribution, — Great Britain, vScandinavia, Finland, north 

 Russia, Bohemia, Germany, France, SjDain, Portugal, and Kamschatka. 



