308 THE NATURAL HISTORY 



terior, how many of the most interesting pages of 

 nature's great book of wonders should we pass over 

 unread ! How little, for instance, should we know of 

 the commonest of our molluscous animals, beyond the 

 generic and specific characters of the habitations of 

 the shell-bearing species, except that they remorse- 

 lessly devour our cabbage and other cultivated plants, 

 or disfigure them with their slimy trails as they crawl 

 over them, if the comparative anatomist, undaunted 

 by their repulsive appearance, had not by means of 

 skilful dissection learnt something of their wonderful 

 structure, and given us the result of his investigations ! 

 In the early days of Conchology, it was held sufficient 

 to study the shells only of these animals, and the 

 possessor of an extensive collection of such shells might 

 have been intimately acquainted with the name, geo- 

 graphical distribution and proper place in a systematic 

 arrangement, of every species in his cabinet, without 

 necessarily knowing anything of the mollusca them- 

 selves. Now, however, the Conchologist has given 

 place to the Malacologist, and this gentleman, not con- 

 tent with examining, describing and naming the shell 

 independently of its inhabitant, curiously questions 

 the latter as to its habits and internal structure ; and 

 in the case of those which possess a single shell 

 (univalves) he literally learns the relationship of each 

 species from, the animal's own mouth. In this way we 

 come to know, among other things, that as a rule 

 slugs and snails are more liberally provided with teeth 

 than any other animals in the parish ; one of our 

 slugs, for instance, actually possessing no less than 

 twenty-eight thousand, they are not, however, all in 

 use at the same time. The dental apparatus of our 

 univalves may be described as a tube lined with teeth 

 set upon flattened plates, collectively called the lingual 

 ribbon. One extremity of this ribbon is open, and 

 spread out like a tongue, teeth upwards, on the floor 

 of the mouth, so as to occupy in fact the same relative 



