D THE NAUTILUS. 



free part of the last wliorl having sharper, more widely-spaced rib- 

 lets. Internal axis slender, moderately gyrate in the later whorls. 



Length 24, greatest diam. 1.8 mm. 



Length 22.5, greatest diam. 1.9 mm. (truncate). 



Collected at " La Lechuza," Monte Toro, by Mr. Charles T. 

 Ramsden, to whom the species is dedicated. 



This is a much larger shell than B. booksiana Gundl., with less 

 swollen spire, and much less strongly gyrate axis. The basal carina 

 is visible on more whorls, the neck is shorter, and the sculpture less 

 regular. It is a very interesting addition to the subgenus Gyraxis. 



REMARKS ON CLASSIFICATION OF THE UNIONIDJE. 



BY L. S. FRIERSON. 



In 1820 and in 1831 C. S. Rafinesque published descriptions of a 

 large number of Unionidce. Of these, he is credited in the '* Syn- 

 opsis of the Naiades, C. T. Simpson, 1900," with but seven or eight 

 species. Conrad, having access to specimens labelled by Rafinesque, 

 gave a list of such species as he identified. Except in such cases as 

 when a patent error can be shown we are bound to accept Conrad's 

 identifications. 



The fact that Conrad made mistakes at times, can have no weight, 

 for no author is free from these. Conrad, however, only awarded 

 to Rafinesque those species described in 1820. Those described in 

 1831 have uniformly been dumped by all subsequent authors (known 

 to the writer) in the trash-pile of " indeterminate Unionidse." There 

 is no valid reason for this, as several of these latter species are 

 clearly and unmistakably recognizable. In place of seven or eight 

 species, Rafinesque is entitled to precedence in at least thirty. 



An annotated synoptical table is is process of making, and will be 

 published shortly. Because of the important bearing of these facts 

 upon modern classification, this preliminary sketch is given, from 

 the latter point of view, for our author was a genius in the art of 

 proposing genera. 



(1) LEPTODEA Rafinesque, 1820. Type leptodon Rafinesque 

 (= tenuissimus Lea). If this species should prove to be congeneric 



