1892.] NATURAL SCIENCES OF PHILADELPHIA. 387 



PRELIMINARY OUTLINE OF A NEW CLASSIFICATION OF THE HELICES. 



BY HENRY A. PILSBRY\ 



For several years the writer has been accumulating data bearing 

 upon the natural classification of the Helicoid land snails. It has 

 been thought desirable to place before students of this group some 

 of the general results attained, and to invite their friendly crit- 

 icism. 



It will be understood that the consideration of many important 

 points, such as the relations of Helices to certain Bulimoid groups, 

 must be omitted from so brief and synoptical a paper as this ; the 

 author's aim being simply to place before malacologists the outlines 

 of a classification essentially modern and essentially original. It 

 can scarcely be expected that an arrangement in which most of the 

 traditions of our Fathers in Conchology have been disregarded, 

 will prove acceptable to all, or, indeed, in all respects worthy of 

 acceptance ; but it is hoped that it will be found an improvement 

 on'previous systems. 



The anatomical details of numerous groups herein for the first 

 time described will be figured in the author's more elaborate work 

 now in preparation, to be issued in 1893.^ 



The notes given below under each genus must not be taken for 

 complete generic diagnoses. I hold that for the establishment of 

 genera the characters of the shell must be taken into account, as 

 well as those of the genital system and of the jaw and lingual 

 ribbon. For the formation of groups higher than genera, certain 

 modifications of the genitalia seem to be most constant and availa- 



^The principal authorities consulted are the following : 



Binney, W. G., Terr. Moll. U. S. vol. V, etc. 



Pfeffer, Georg, Beitr. zur Kenntniss Mex. 1. u. fr.-w. Conch., etc. 



Fischer, Paul, Numerous papers in the Jour, de Conch, and Moll. Mex. et 

 Guat. 



Hedley, Chas., Proc. Roy. Soc. Queensl. and Proc. Linn. Soc. N. S. W. 



Hutton, F. W., Trans. N. Z. Institute. 



V. Ihering, H., Morphol.u. Syst. des Genit. von Helix. This paper, ihe ers/er 

 Thiel of which is before me, is a very valuable one and indispensable to the stu- 

 dent of Pulmonale morphology. 



Lehmann, Die Lebenden Schn. Stettins. 



Pilsbry, H. A., Proc. Acad. Nat. Sci. Phila., 1888-1892. 



Schmidt, A., Des Geschlechtsap. der Stylom. 



Schako, G., Numerous papers. 



Semper, C, Reisen im Archip. Phil. Landmoll. 



Suter, H., Trans. N. Z. Institute. 



Tapparone Canefri, C, Annali Mus. Civ. Geneva. 



