CLAUSILIA. 89 



All the members of this genus are sinistral. 



1. C. EUGOSA (wrinkled), 



Fusiform, purplish brown, but varying in colour ; marked 

 with small streaks of white ; closely and irregularly striated 

 in the line of growth ; whorls ten to thirteen ; spire tapering 

 to a blunt point ; mouth pear-shaped, expanding like a 

 funnel, angulated above ; plications two on the pillar, with 

 two or three ribs between them, a plication behind the 

 pillar lip, near which is a spiral fold ; one or two teeth 

 inside the outer lip ; umbilicus narrow ; clausilium shaped 

 much like a " shoehorn." 



This common shell is distributed throughout the 

 whole of the British Isles, and is usually found on 

 stone walls, rocks, rough bark of trees, and sometimes 

 on sand-hills. It is very variable both in colour and 

 markings. The smaller forms seem to be found, as 

 might be expected, in northern and exposed situa- 

 tions. I have found it abundantly on the banks of 

 the River Bann, adhering to stones which are com- 

 pletely covered at high tides. 



Var. I. albida. Whitish. 



Var. II. Everetti. Smaller. 



Var. III. gracilior. More slender. 



Var. IV. tumidula. Shorter, more ventricose. 



Var. V. dubia. Larger, more ventricose. 



Var. VI. Schlechtii. " Generally larger, more 



