164 GASTEROPODS. 



Horizon and localities. Silurian, Trenton limestone : Glen- 

 coe, McOune station (Pike county), Allerton (St. Louis 

 county), Bailey landing (Perry county). 



Phanerotinus paradoxus WINCHELL. 



Plate lii, fig. 7. 



Phanerotinus paradoxus Winchell, 1863 : Proc. Acad. Nat. Sci , Phila., p. 21, 

 Phanerotinus paradoxus Hall, 1879 : Pal. New York, vol. V, pi. ii, p. 60, pi. 



xvi, fig. 16. 

 Eccyliomphalus paradoxus Miller, 1890: N. A. Geol. and Pal., p. 403. 



Shell rather small, planorbiform ; volutions not contigu- 

 ous, about four in number, very gradually enlarging to the 

 aperture, which is circular. Surface smooth, with indistinct 

 lines of growth. 



Horizon and localities. Lower Carboniferous, Lower 

 Burlington limestone: Louisiana (Pike county). 



Genus Capulus MONTFORT. 



Until quite recently there has always been a considerable 

 diversity of opinion as to what term should be really applied 

 to the Paleozoic group of gasteropodous shells commonly re- 

 ferred, by most American writers, to Platyceras of Conrad. 

 The described species of this group have been variously and 

 indifferently assigned to Capulus, Montfort, Pileopsis, Lamarck, 

 Actita, Fisher von Waldheim, Platyceras, Conrad, Acroculia, 

 Phillips, Orthonychia, Hall, and some other genera. Of these, 

 Capulus and Platyceras have become at last generally adopted, 

 the former having preference with most European and the 

 latter with the majority of American authors. 



The two genera last mentioned are practically co-extensive, 

 and since the first has precedence of more than thirty years- 

 it should be used instead of the second. Even if the group 

 to which Conrad gave the name Platyceras were a valid one, it 

 is very questionable whether the term could stand, inasmuch 

 as it has been pre-occupied for three-quarters of a century. It 

 has long been known that Geoffrey in 1764 proposed for a 

 genus of Coleoptera the name Platyceras, a term which was 

 later employed by Latreille, and which continues to the present 



