BKRSTON : NON-MARINE MOl.LUSCA OF LLANDUDNO. I3I 



hide, and remain in a quiescent state ; if one goes collecting at this 

 time specimens may be usually found in abundance. 



But if, say, a few weeks or even days later, the collector again 

 visits the locality, even after or during rain, he may not find a single 

 specimen ; either the atmospheric conditions are different from those 

 which obtained on the former occasion, and thus do not entice the 

 animals from their lairs, or else having buried or hidden themselves 

 so effectually, they have not had time to make their appearance ; 

 hence the collector comes to the conclusion that the creatures have 

 either departed or been destroyed, whereas they are there, and under 

 suitable conditions can be found. Conditions which entice out one 

 species will not suit others. As instances of this, it may be men- 

 tioned that H. virgata and H. caperata do not seem to mind either 

 warm or cold weather. 



Birds and animals, too, may have something to do with the dis- 

 appearance of certain species from particular localities. It is a 

 well-known tact that several species of birds feed largely on snails, 

 especially in spring ; consequently any material increase of bird life 

 will be followed by a corresponding decrease in moUusca. A few 

 years ago the crop of a wood-pigeon was found crammed to repletion 

 with small molluscs, no less than 578 being counted, chiefly Vitrea 

 cellaria and Hygromia rotundata. It is very evident that a district 

 frequented by these birds would very soon be completely cleared out 

 of snails. Without doubt birds know the best time to search for 

 such food, i.e., the most favourable condition of the atmosphere, 

 either during or after rain, or in early morning, before the animals 

 return to their shelters. 



Thrushes, rats, mice, water-voles, and even rabbits feed on snails, 

 so that should any of these animals unduly increase, and we know 

 they frequently do so, especially the rodents, and other sources of 

 food become scarce, the snails will have to pay heavy toll, and may 

 even be exterminated. 



The following list of varieties of H. nemoralis found among the 

 ninety specimens which I collected, I have tabulated and compared 

 with that given by Mr. Roebuck. 



The slugs seem very poorly represented in Llandudno district. 

 Personally, I found very few species, those named being copied from 

 the lists of Messrs. Roebuck and Tomlin. 



Limax maximus Linne. — Scarce. 



var. cellaria Miiller. — Tal-y-Cafn, Llangwystenin. 



Limax arborum Bouchard-Chantereaux. — Abundant. Beech 

 Woods, Llanrwst, Gloddaeth Woods. 



