120 CONCHACEA. 



Shell suboval, oblique, very convex, pellucid, and covered 

 with extremely fine, concentric, rather obscure striae ; umbones 

 obtuse, placed nearest the anterior side ; hinge with one central 

 and two lateral teeth in the right valve, and two oblique car- 

 dinal and one lateral tooth in the other ; colour pale ash. A 

 little more than an eighth of an inch in length ; and somewhat 

 more in breadth. 



First discovered in a ditch at Duddingston Loch, near Edin- 

 burgh, by my friend James Gerard, Esq. I have since found it 

 in the ditch at the north end of the Loch, and also in a ditch 

 at Hunter's Bog, King's Park. Thompson says it inhabits the 

 north and south of Ireland. 



Turton, in his Manuel, says it is found "in most streams and 

 brooks," but although I have examined numerous localities in 

 England, Ireland, and Scotland, I have not found it so common 

 as he alleges. 



3. PiSIDlUM OBTUSALE, pi. XXIII, f. 9- 



Pisidium obtusale, Alder, Mag. Zool. and Bot., II, p. 118; 

 PfeifiFer, p. 125, pi. 5, f. 21, 22; Brown, Edin. Journ. Nat. and 

 Geo. Science, I, p. 413; lb., Illust. Conch., p. 94, pi. 39, f. 24; 

 Thompson, Ann. and Mag. Nat. Hist., VI, p. 53 ; Cyclas ohtu- 

 salis, Lamarck, V, p. 559, No. 6 ; Pera gibba, Leach, MSS. 



Shell oblique, ventricose, heart-shaped; sides somewhat une- 

 qual; beaks prominent, and obtusely rounded; pellucid, yel- 

 lowish-white, or pale horn-coloured ; with extremely minute, 

 concentric, thin striae; the lower edges of the valves rather 

 sharp. Length an eighth of an inch ; breadth an eighth and a 

 quarter ; thickness not quite an eighth. 



I found this new British species plentiful in a ditch at the 

 Wells of Weary, immediately under the columnar greenstone 

 rocks, west end of Arthur's Seat, near Edinburgh, which is now 

 covered up by the railway. Thompson gives as localities in the 

 north of Ireland, a drain near Bangor, and a pond at Portavo ; 

 and at Finnoe, Tipperary, in the south. 



4. Pisidium appendiculata, pi. XXIII, f. 10. 



Pisidium appendiculata, Brown, Illust. Conch., p. 95, pi. 39> 

 f. 25; Cyclas appendiculata, Leach, MSS.; Turton, Man., p. 15, 

 f. 6 ; Pisidium Henslowianum, Thompson, Ann. and Mag. Nat. 

 Hist., VI, p. 54; Tellina Henslowinana, Sheppard, Linn. Trans., 

 XIV, p. 150. 



