Specific Bank o/Limax cinereo-iiiger, Wolf. 227 



observatioTis, which are both numerous and accurate, made by 

 Mr. Asliford. 



Another point of difference between the two forms under 

 consideration is afforded by the radula, whicli is only second 

 in importance to tlie reproductive organs as affording a 

 criterion for the differentiation of molluscan species. Indeed 

 some authors ascribe to it a much liigher value in this 

 regard. The differences in the radulse of L. maximus and 

 L. cinereo-niger, as figured by Heynemann, who was the 

 acknowledged foremost limacologist of his time, in his paper 

 " Ueber Schneckenzungen der Gattung Limax''^ (Mai. Bljitt. 

 1863, pp. 200-218), are very striking. The teeth of L. 

 maximus are simple in form nearly throughout, only the 

 extreme outer teeth being shown as bifid, whereas in L. cinereo- 

 niger the extreme outer teeth are simple, and the side-teeth 

 are throughout bifid and even trifid. 



The external characters, as I have pointed out more than 

 once, are sufficiently distinctive to make L. cinereo-niger a 

 particularly easy species to recognize. I have had ample 

 opportunity for forming a judgment in this respect, as by far 

 the greater proportion of the British specimens known have 

 passed through my hands. 



The sculpture of the two species is markedly different in 

 character. In L. maximus the rugosities of the body are 

 small, fine, and closely set in comparison with L. cinereo- 

 niger , which has them large and coarse, with deep furrows 

 separating them. In this respect it resembles Arionater, and 

 there can be little doubt that it is frequently mistaken for that 

 species by inexperienced conchologists, more especially as the 

 colour is often very similar, L. cinereo-niger being nearly 

 always a very dark species, usually black, with but lew pale 

 markings, often none. 



The differences in colour are important. One of the most 

 striking characters of L. cinereo-niger is that the foot-sole is 

 what may be loosely called " trifasciated," the tw^o side-areas 

 (longitudinal) being black, blackish, or dark-coloured, with 

 the central area white. This is never the case with true 

 L. maximus, but is a fairly constant character in L. cinereo- 

 niger. I have on one or two occasions seen juvenile examples 

 with the whole foot-sole Avhite, but never adults. 



The coloration of the shield offers another ready mark of 

 distinction. L. maximus always has this part maculated or 

 marbled ; but in L. cinereo-niger there are no maculations or 

 marblings, the shield being invariably of a uniform dark 

 colour. 



A less constant but very convenient character of L. cinereo- 



