CLASSIFICATION. 



Classification. 



If it be true that too many cooks spoil the broth, the same may be said of the 

 numerous systems of classification which have been put forward for the Mollusca. 

 A friend of mine, who has a large collection under his charge, despairing of ever 

 arriving at the right method, once said in the bitterness of his heart that he was 

 thinking of adopting an alphabetical classification based upon genera. As one 

 would fain believe that the main object of classification is arrangement according 

 to affinities real or supposed, it is evident that such an act, if adopted for a 

 collection and not for a catalogue, would be a piece of zoological suicide. It 

 certainly may be argued with irresistible logic that, since the systems of clas- 

 sification are so numerous, they cannot all be right, and that the chances are 

 against any one that may be selected. 



But, after all, a collector would hardly like to store his fossils on principles 

 which might very well commend themselves to a dealer; and rightly or wrongly it 

 his duty to attempt some system of classification which shall be an aid to 

 comparison as well as to differentiation. Then arises the question, for us more 

 especially important, what is the best basis for a classification of the Gasteropoda ? 

 To many malacologists lingual dentition commends itself as the means whereby 

 the most philosophic system of classification may be effected, whilst others incline 

 to attach more weight to the shell itself. Hence, S. P. Woodward, in the ' Manual 

 of the Mollusca,' divided the Prosobranchiata, with which we are mostly con- 

 cerned, into Siphonostomata and Holostomata, the former including the bulk of 

 the carnivorous Grasteropods — always excepting Natica. But the exception of 

 this large and ancient genus is an awkward one, and it proves that the divisions 

 adopted do not coincide with the divisions based on the modes of nutrition. 

 There is also another difficulty in connection with the arrangement of the 

 'Manual of the Mollusca,' viz. placing Gerithium and Aporrhais amongst the 

 Holostomata. It matters nothing whether these are vegetable feeders or not; 

 clearly their shells are not holostomatous in the strict sense of the term, although 

 on other grounds the affinities of the animal may be more with the Holostomes 

 than with the Siphonostomes. This subject has been well discussed in the 

 ' Palasontologica Indica ' by Stoliczka, who arrived at the conclusion that such 

 divisions as Siphonostomata and Holostomata might be accepted provisionally, 

 but without giving such divisions any prominence. 



Any system based mainly on lingual dentition cannot exactly commend itself 

 to a palaeontologist. The palaeontology of the Gasteropoda is sufficiently empirical 

 without importing this fresh element of uncertainty. Who can say what was the 

 lingual dentition of Nerinaa ? Hence, whilst admitting to the full the value of 



