TIIK NAUTILUS. 7 



(Ten-. Moll., U.S.) the (li,snieni])enucnt of the gemis so imieli de- 

 manded by the number of its 8pecie.s, founding the distinction on 

 the sliell alone." 



It was as if the court had made up its mind beforehand, but had 

 waited for the evidence to establish the decision, and when the evi- 

 dence did not support it, the decree was rendered just as the court 

 had intended all along. jNIany of these so-called genera of Helix 

 have no value at all, and others so little as to be almost worthless 

 for purposes of classification. Our well-known Mesodon runs into 

 Triodopsis, and Arionta and Aglaia cannot always be separated. 

 Tryon at one time placed Helix devius, Gould, in the genus Me.sodon, 

 and at another time he, as well as Mr. W, G. Binney, called it a 

 Triodopsis. Tryon put Arionta townsendiana, Lea, in the genus 

 Mesodon, and Mr. Binney regards Aglaia hillebrandi, Xewc, as a 

 varietal form of Arionta mormonum. And I might give such illus- 

 trations to the end of the chapter, all of which go to show that even 

 among the savants these so-called genera are well nigh valueless. 



But let ub suppose that in any of the larger genera there is a chain 

 of species varying from the. type to those which are very unlike it ; 

 that the variation is very gradual throughout the species. I cannot 

 see that dividing such a genus into a dozen, a hundred, or a thousand 

 genera is going to help the matter or give us any clearer insight into 

 the relationship of the species. I think that the classification should 

 be founded on nature, or in other words, that nature should d(j the 

 classifying, and that our eflforts should be directed to deciphering the 

 Old Dame's work. And if a distinction does not exist between cer- 

 tain so-called species and genera, it is useless to put it there, as it 

 will simply require that somebody in the future, when the truth is 

 reached, will have to throw it out. 



The genus Unio, with its thousand species and endless variations, 

 has l)een divided into a number of sub-genera by the genus makers ; 

 but a Unio is a Unio for all that, and the merest novice in conchol- 

 ogy would recognize it as such in a moment; while probably not 

 one conchologist in a hundred could tell a Bariosta, Raf, from a 

 Hyridella, Swains. Dr. Isaac Lea showed his great knowledge of 

 this subject when he groujjed them into mere divisions founded on 

 form and sculj^ture. 



I think the time has come when a healthful reaction frou) this 

 fever of creating genera and species should set in. Such work simply 

 renders the science of conchology contcni])tible, and it is a veritable 



