172 PROCEEDINGS OF THE MALACOLOGICAL SOCIETY. 



against drying of the eggs, is Clausilia hijMcata, which, freely 

 anabatic as it is in wet weather, normally lives on the ground in 

 places (at Mortlake, Cambridge, and Purfleet) which are neither 

 particularly dry nor very wet. There is a difference of opinion 

 about the other species of Pupa : Kennard and Woodward ^ say 

 that Pupilla (which includes marginata, which lives in dry places 

 on the ground) lays eggs, while Lauria (v/hich includes anglica, 

 living in wet habitats) is viviparous ; Moquin-Tandon and Steenberg 

 agree that marginata is viviparous, and Jeffreys says that anglica 

 does not appear to be viviparous ; no one says anything about the 

 reproduction of secale. Of other geophobic species, Vallonia costata 

 is oviparous, while of the habit of Vertigo alpestris nothing seems 

 to be known ; I may, therefore, hazard the prophesy that it will be 

 found to be viviparous, especially as Moquin-Tandon (Histoire, i, 

 262) says that perhaps most Vertigoes are. 



[Dr. Bowell and Professor Cockerell suggested in the discussion 

 that dispersion of Balea from tree to tree was effected by birds 

 carrying branches (cf. H. W. Kew, "Dispersal of Shells," 1893, 

 p. 164). Mr. Oldham thought it more likely that birds like the 

 tree-creeper picked them up accidentally on feet or feathers off 

 the trunks in wet weather when the snails came out of the 

 crevices ; both Balea and P. umhilicata had exceptionally sticky 

 mucus.] 



^ Proc. Geol. Assoc, xxviii, 170. 



