70 PROTECTIVE COLORATION chap. 



in Cornwall are banded with rings of colour, especially with 

 black and white, in a more varied and striking way than any 

 other specimens that have ever occurred to my notice. I am 

 inclined to refer this peculiarity to a tendency towards protective 

 coloration, since the rocks on which the Purpura occvirs are 

 often banded with veins of white and colour, and variegated to a 

 very marked extent. 



Ovula varies the colour of its shell from yellow to red, to 

 match the colour of the Gorgonia on which it lives. The same is 

 the case with Pedicularia, which occurs on red and yellow coral. 



Selix desertorum, by its gray -brown colour, harmonises 

 well with the prevailing tint of the desert sands, among which 

 it finds a home. Benson observes that the gaudy H. haemastoma, 

 which lives on the trunks of palm-trees in Ceylon, daubs its shell 

 with its excrement. Our own Buliminus ohscurus, which lives 

 principally on the trunks of smooth - barked trees, daubs its 

 shell with mud, and must often escape the observation of 

 its enemies by its striking resemblance to the little knots on 

 the bark, especially of beech trees, its favourite haunt. Some 

 species of Microphysa, from the West Indies, habitually encrust 

 their shells with dirt, and the same peculiarity in Vitrina 

 has already been mentioned. Ariophanta Bohertyi Aldr., a 

 recent discovery from Sumatra, is of a green colour, with 

 a singularly delicate epidermis ; it is arboreal in its habits, 

 and is almost invisible amongst the foliage.-' Many of our 

 own slugs, according to Scharff, are coloured protectively 

 according to their surroundings. A claret -coloured variety 

 of Arion ater occurred to this observer only in pine woods, 

 where it harmonised with the general colouring of the ground 

 and the pine-needles, while young winter forms of the same 

 species choose for hiding-places the yellow fallen leaves, 

 whose colour they closely resemble. Limax marginatus ( = arho- 

 rum Bouch.) haunts tree trunks, and may easily be mistaken 

 for a piece of bark ; Amalia carinata lives on and under the 

 ground, and in colour resembles the mould ; Arion intermedins 

 feeds almost exclusively on fungi, to which its colour, which 

 is white, gray, or light yellow, tends to approximate it closely ; 

 Geomalacus maculosus conceals itself by its striking resemblance 

 to the lichens which grow on the surface of rocks, and actually 



1 Nautilus, vi. 1892, p. 90. 



