130 THE NAUTILUS. 



for Poecilozonites, which has the dentition, radula, etc., of Zonites, 

 but no mucous pore f Or for Streptodyla Hgulafa because it has a tail- 

 pore while some of the other Streptodylas with very similar shell and 

 anatomy have none ? 



Passing over Dr. v. Ihering's limitation of the family Helicidce, 

 which I can readily prove to be untenable, I may be excused for 

 making some mention of the new genus Neohelix. Several years 

 ago, when I recognized the essential identity of Polygyra, Triodopsis, 

 Mesodon, etc., 1 selected the first of these as a generic name for the 

 whole, because it was the oldest name proposed. In common with 

 the vast majority of modern naturalists, I recognize the rule of 

 PRIORITY as absolute. Were it otherwise I could change Dr. v. 

 Ihering's Neohelix to " Paleohelix" on the ground that he includes 

 H. toivnsendiana Lea in it, that species being really a Lysinoe ! ^ Or 

 on the ground that Neohelix is a misnomer, for they are not " new " 

 helices at all, but a much older, more archaic type than the genuine 

 Helix of Europe! The latter, indeed, are the new Helix, being the 

 most highly specialized of all Helices. 



As to V. Ihering's group " Parahelix,'^ formed to include " all 

 Helices not Helicidce or Neohelix," it seems to me to be an entirely 

 unnecessary addition to nomenclature ; for it would include forms 

 in no way related to one another. The anatomy may be unknown 

 to Dr. V. Ihering, but, as may be seen by glancing over my paper 

 on the genera of Helices, it is not unknown to some others. It is as 

 if one were to propose a " family " to include all carnivora not 

 belonging to Felidce or Canidce. 



In respect to the former v.dde range of Partula, it should be said 

 that Oppenheim's " Partula " are Buliminus, and Heilprin's are Bul- 

 imulus; both groups exist in the same regions to-day. A word on 

 the former connection of New Zealand and South America. The 

 only elements the two faunas have in common seem to be either (1) 

 cosmopolitan genera, all of which probably date back to the Car- 

 boniferous period, or (2) genera of like ancient origin, but which 

 have been replaced in the Tropics and the North by the more mod- 

 ern types developed by the more active competition. At the same 

 time, I offer this simply as an opinion, which may stand or fall. In 

 any case, the hypothesis of Prof Hutton and Dr. von Ihering is of 

 great interest, and cannot fail to stimulate investigation of this most 

 important question. 



^ V. Ihering probably meant II. ptychophora Brown, a Mesodon formerly 

 confused with the other species. 



