BOYCO'l'T : l.OCAt, VARIATION OK Cl.AUSlI.IA BIDEN'l'ATA. 



23 



;; 



1 ;: 



'z[. 









rp 



m ;e 



:: :: 



:: ::: 













o a$ 90 95 100 TO 5 no 115 120 125 13 ( 



Altitude m.m. 



Fig. 2. — Diagram of the distribution of the altitudes of the shells from 

 loci E (lined) and H (dotted), both expressed as if the total 

 were 100. 



Fig. 3. — Diagram of the mean altitudes and diameters of the shells from 

 the different loci. 



Litnnaea glabra Miiller at Caldon Low, Staffs. — In March of this year 

 Z. glabra was found in great numl)ers in a small grass-choked ditch, about eight 

 yards long by two feet wide, very close to the south edge of the limestone of which 

 the Weaver Hills ridge consists. The ditch is practically eleven hundred feet above 

 sea-level. The only other species noticed was Pisidittm personatum Malm. On 

 the occasion of a second visit in June the ditch was quite dry, but L. glabra was 

 still present and very common amongst the grass roots and under stones, the large 

 numbers of newly-hatched shells being especially noticeable. — W. E. Alkins 

 (Read before the Society, June I2th, 19 18). 



