THE NAUTILUS, 148 



3. The remarks about Plejona which were made by both Mr. 

 R. B. Newton and Mr. Smith indicate unfamiliarity with nomencla- 

 torial questions, which indeed are sometimes sufficiently puzzling. 

 But there is no ambiguity or difficulty in the case of Plejona, if the 

 rules are complied with. Bolten's genus (for the period remarkably 

 homogeneous) contains 24 species, all of which are identifiable, in 

 terms of the older authors, and only one of which is a fossil. The 

 first (fossil) species is based upon four very fair figures of " spiny 

 murices," which Argenville referred to one species, but which repre- 

 sent three or four, as species are now reckoned. If we prefer to take 

 our type from the first species in Bolten's list, it reduces itself to a 

 simple process of elimination which leaves us with V- spinosa (one 

 of those figured) as the type. If we regard the solution as vague, 

 there still remains my absolute right to revive Bolten's name for any 

 species contained in his list, and for which there is no prior valid 

 name. This I did several months before Mr. Newton proposed 

 Volutospina for the same shell. 



If we reject Bolten's P. fossilis as vague, we are left to take 

 Voluta ebraea, his second species, as type, which involves the loss of 

 the generic name Voluta (Lam.), as now universally used, which it 

 seems to me would be foolish, since the preceding method enables us 

 to retain Voluta for V. musica and its allies without upsetting any 

 accepted name. 



I regard Athleta (rarispina) Conrad as a good genus, perfectly 

 distinct from Plejona (spinosa) Bolten, as well as from the V. petrosa 

 deformities. The latter were erroneously referred to the genus 

 Athleta, which they really only superficially resemble, and conse- 

 quently any attempt to use Athleta for the spinosa group is fallacious. 

 Athleta does not occur in America, but there are probably three 

 European species. Wm. H. Dall. 



Smithsonian Institution, March 6, 1907. 



PUBLICATIONS KECEIVED. 



West American Mitrid^e By Mrs. M. Burton Williamson 



(Proc. Biol. Soc, Washington, xix, Dec, 1906). Mitra idx, fultoni, 

 lowi, and the Peruvian M. orientalis are discussed at length and 

 with the exception of M. lowi, figured. A useful work, since these 

 black Mitres have been involved in some confusion. 



