28 THE ZOOLOGIST. 
II. AQUATIC MOLLUSCA. 
BIVALVES (CONCHIFERA). 
Order LAMELLIBRANCHIATA. 
Fam. SpH®= RUDE. 
Spherium corneum. The Horn-coloured Spherium.—Common 
in several small lakes in the district; and in Lough Conn, Mayo, 
T have found also the var. flavescens. 
Pisidium fontinale. The Stream Pea Shell.—Common. 
P. pusillum. The Little Pea Shell.—Still more common and 
numerous than the last-named. 
P. nitidum. The Glossy Pea Shell.—Cloonagh Lough is the 
only locality where I have obtained this bright little shell. 
P. roseum. The Rosy Pea Shell.—Rather rare. 
Fam. UNIONID2. 
Unio margaritifer. The Pearl Mussel.—Mr. Little, of the 
Moy Salmon Fishery, has given me several very fine specimens of 
this shell, taken by the fishermen from the Moy above the weirs 
at Ballina. I have also got some from Mr. Symes, of the 
Geological Survey, procured by him, I believe, in the river at 
Newport, Mayo. 
Anodon cygnea. The Swan Mussel.—Numerous in Cloonagh 
Lough, and Mr. Little has given me two young shells from the 
Moy. 
Order PECTINIBRANCHIATA. 
Fam. NERITIDE. 
Neritina fluviatilis. The River Neritina.—This peculiar and 
pretty little shell I have found in Cloonagh Lough, a little moor- 
land lake about a mile and a half from Ballina, on the Mayo side, 
and in Lough Talt, situated in the Ox Mountains, Sligo. Dead 
shells have also been taken from the mill-race of Bunru Mills, 
near Ballina. 
Fam. PALuDINIDz. 
Bythinia tentaculata. The Tentacled Bythinia. — Common 
everywhere. 
