r),S LIMAX CINEREO-NIGIR. 



The OLFACTORY sense in L. cinereo-niger is remarkable for its power and 

 precision. M. Colbeau relates that the tine siiecimen of var. malacohgm-um 

 in his possession escaped many times from the box in which it was confined, 

 through a small hole five mill, in diameter, and after wandering about 

 several days in the garden, on two occasions re-entered the box by the same 

 small hole, evidently attracted by the mushrooms grown therein. 



Variation. — Colour variation in the Limacidaj would seem to reach its 

 acme of development in this species, individuals of which display all shades 

 of colour, ranging 'from uniform wliite, throuifh grey, yellow, brown, and 

 red to uniform black, with all the variations to which their combinations 

 may give rise. This marvellous variety in colour and marking leads us to sus- 

 pect, as suggested by Simroth, that this rich and elaborate pigmentation is 

 of high biological importance to this species in the struggle for existence. 



The complex causes which influence or inhibit the evolution and external 

 disposition of colouring matter in the Limacidte are still little understood; 

 it has, however, been demonstrated by Simroth that the intensity and shade 

 of tlie various colourings are dependent in a measure upon temperature, 

 especially during the growth period. Cold, inclement seasons or districts 

 favour the increase of the blaclc pigment, and pale or entirely eradicate 

 the red, while warm seasons or areas foster the development and intensi- 

 fication of the red pigment, resulting in the gorgeous varieties recorded 

 from Italy and other southern countries ; but it must not be overlooked 

 that the distribution and character of the external pigmentation is also 

 largely influenced by the necessities of the animal, either by inducing a 

 closer assimilation to the peculiarities of the environment, and therefore a 

 more effective concealment from its enemies, or conversely by the develop- 

 ment of a brighter colouring, rendering it more conspicuous, and therefore 

 probably acting as a warning colour.' 



Like its close ally Llmax maxlmus, the present species may also be 

 regarded as trichroic or triple- tinted in its pigmentation, and has probably 

 passed through a similar course of colour-changes, but the colour-develop- 

 ment has advanced much further, a response to the more freely exposed life 

 it leads and the consequent greater vicissitudes of temperature, etc., to 

 which it is subjected. 



The probable sequence of its pigmentary evolution is shown by the 

 primary or secondary tints sometimes extending over the locomotor or 

 mid-area of the sole, beyond the darker tertiary colouring which has not yet 

 advanced beyond the side areas and is still very superficial in its disposition ; 

 further evidence of the progress of colour evolution is adduced by Simroth, 

 from which we gather that in the youthful stages of the species in the 

 more advanced districts there is a prevalence of the simple colouring which 

 characterizes adults in those less favourable or more remote, as in L. mon- 

 tunus of South Tyrol, L. engadinensis of East Switzerland, etc. 



L. cinereo-niger, judged by its more extended range altitudinally and 

 also geographically wherever suflicient and jirecisc observations have been 

 made, by the situations it usually inhabits, by the more primitive character of 

 its teeth, by the point of attachment of the penial retractor, and other pecu- 

 liarities, is probably a more primitive and earlier form than L. Mii.rimus, but 

 tlie extreme climatic conditions under which the species lives, have enabled 

 it to outstrip in its external pigmentation the L. ma.rimus, which evinces 

 such a partiality for the vicinity of human abodes, and is therefore more 

 prone to be carried by commerce to, and become naturalized in distant lands. 



1 Moiiog., i., p. 327 and p. 330. 



