PLANT-EATING MOLLUSCS 199 



Following down the tide to extreme low-water mark, we get 

 to the Laminaria zone, occupied by broad brown sea-weeds of 

 that genus, which are always partly covered by water. These 

 frequently exhibit the ravages of molluscs, one of the chief de- 

 predators being a small smooth relative of the Limpet (Helcion 

 pellucidum), the shell of which is beautifully ornamented by 

 radiating blue lines. This little creature lives entirely under 

 water, and eats out a home for itself in the sea- weed, sometimes 

 in the stem-like part, but most frequently in the attached region, 

 which is expanded and fixed to the rock by a number of root-like 

 branches. This limpet either wanders at large over the weed 

 or may feed near its home, scraping out roads for itself in the 

 neighbourhood of its dwelling. 



LAND-SNAILS AND SLUGS (fig. 437). Among terrestrial forms 

 very interesting observations have been made which prove clearly 

 that the sense of smell is used in hunting for favourite sorts of food. 

 Furtado observed the tactics of a common Garden Snail (Helix 

 aspersa) in the neighbourhood of a young banana plant which 

 had been placed in a verandah overlooking a small court. He 

 removed the snail, throwing it into the court to a distance of 

 several yards. Next morning the snail was back again in the 

 same place, and was again removed to a similar distance, its 

 further movements being carefully watched. The following 

 morning it was seen on the rail of some steps leading up to 

 the verandah, and in the course of the evening resumed its 

 march, ultimately reaching once more the desired spot. Cooke 

 (in The Cambridge Natural History) quotes some interesting 

 observations narrated by Moquin-Tandon in regard to the habits 

 of the Black Slug (Arion ater) and the Great Slug (Limax 

 maximus], both which are in the main vegetable feeders. His 

 remarks run as follows: "Anyone can experiment for them- 

 selves on the olfactory powers of our common snails or slugs. 

 Moquin-Tandon records two interesting cases, one communi- 

 cated to him by letter, the other occurring to himself. His 

 correspondent, a M. Parenteau, was one day walking along a 

 dusty high-road, when he noticed near the middle of the road 

 an empty bean-pod, and two Arions eating it. Attributing the 

 meeting of feeders and food to mere chance, he was walking 

 on, when he noticed a second bean-pod, and, about 2 yards 

 away from it, a third Arion hurrying straight towards it. When 



