54 JOURNAL OF CONCHOLOGY. 



CONTRIBUTION TOWARDS 

 A LIST OF THE SHELLS OF MERIONETH. 



By THOS. ruddy, of Pale, Corwen. 



Sphaerium lacustre. — Plentiful in ponds and ditches. 

 Pisidium fontinale. — Most abundant and general in ditches, 



ponds, &c. 

 Unio margaritifer. — Plentiful in the river Dee. I have seen 



colonies of fifty to sixty together. All the shells are eroded 



at the hinge. 

 Planorbis nautileus. — Llyn-y-Gwernen, near Dolgelly. 

 P. nautileus var. cristata. — With P. nautileus. 



Llyn-y-Gwernen is a small lake two miles from Dolgelly, 



on the road to Cader Idris. It is mostly overgrown with 



water plants. The climate is mild at Dolgelly. 

 P. spirorbis. — Llyn-y-Gwernen, near Dolgelly, and Llyn- 



Creini, near Bala. The latter is a cold moorland lake. 

 Physa fontinalis. — Llyn-y-Gwernen, Dolgelly. 

 Limnsea peregra. — Abundant in pools, lakes, and ditches. 



I have seen it in a lake at Cader Idris, at an altitude of 



about 1,500 feet. 

 L. truncatula. — Common in ditches. 

 L. glabra. — Boggy ditches near Llanderfel. 

 Ancylus fluviatilis. — Abundant and general in the river Dee 



and in mountain streams. — I have seen it at an altitude of 



about 1,000 feet. 

 Succinea elegans. — I picked up one specimen of this in a 



field near Bala. I kept it in a little box from the middle 



of April until the middle of July, in a full sun exposure ; 



and, on opening the box at the end of the three months, 



the creature crawled about quite lively. 

 Vitrina pellucida. — Common and general. 

 Zonites cellarius. — Very common and general. 

 Z. crystallinus. — Plentiful and general. 



J.C, v., April, 1887.' 



