262 OLASSIFICATION. 



chance of finding a vaiying dentition. If this latter proves 

 true, we shall be obliged to concede that there are certain types 

 of teeth which may be found among the species of some of the 

 larger genera, though some of the smaller genera are much more, 

 if not absolutely restricted to one single type of dentition." 



If it be proposed that a single arbitrary standard shall be used 

 because it is arbitrary and hence will remove all doubt as to the 

 position of a given species, then the standard selected should be 

 the most universal and the most apparent — namely, the shell. 

 But if a natural arrangement be attempted, still less can we make 

 account of an}- character which is not in accord with the assem- 

 blage of characters. A natural sequence can only result from 

 an accordance of most of the organs and functions. That denti- 

 tion in the mollusks is a character worthy of study, that it will 

 throw light on manj^ doubtful points, that it will correct many 

 errors is not to be disputed ; but the claims made for it are 

 preposterous ; — for whilst a few hundred species only have had 

 their tongues examined, described and figured, many thousands 

 have been arbitrarily placed and displaced in consequence. 

 Stimpson has examined the tongue of Banella caudata and finds 

 it to be that of a Murex ; accordingly he separates from Ranella 

 a few other species because their shells resemble the shell of 

 Banella caudata and unites them also with Muricidfe and this is 

 practically the course (and necessarily so) pursued by all these 

 dentition S3^stematists. If conchological characters may be used 

 to support the fabric reared upon the knowledge (I had almost 

 written the want of knowledge) of a single structural character, 

 why may thej^ not be equally used against it. Is it not imperti- 

 nent to make use of a few hundred observations of an organ 

 which only pervades a portion of the mollusca, to establish a 

 classification which is frequently in violent contrast with natural 

 affinities ascertained b}^ long examination of all the species, 

 recent and fossil ? 



If the exo-skeleton or shell carries the impress of its animal, 

 its right appreciation will aff"ord us the only possible classification. 

 It is not partial, but pervades nearly the whole mollusca — as 

 well those which have no lingual ribbon ; its universality is 

 the proof of its higher systematic importance ; its relationships 

 are not single, it is the epitome of the modifications of molluscan 

 structure. Supposing the dentition of all living forms to be 

 examined (an impossibility), we are still confronted by the fossil 

 shells, which absolutely refuse to be classified b^^ any other than 

 conchological characters. What shall we do with them ? Shall 

 we use for these ,30,000 species obvious external, universal 

 characters, yet discard these in the recent mollusca for the 

 modifications of a partial character, the very slight observation 

 of which has sufficed to show that it may not be predicated with 



