52 BULLETIN 90, UNITED STATES NATIONAL MUSEUM. 



one has fixed a type-species for Pterygia. Montfort, in 1810, gave 

 a masculine termination to Lamarck's name and called the genus 

 Marginellus. Perry, in 1811, referred his only species of Marginella 

 to the genus Valuta. 



The next reviser of the classification was Schumacher, in 1817. 

 He accepted MargineMa Lamarck, with Lamarck's type. He further 

 eliminates in succession the following new genera, Persicula ( Valuta 

 persicula Linnaeus), Imbricaria {Valuta conus Gmelin), and Cylin- 

 dra {Valuta crenulata Gmelin). The last is a homonym of Cylinder 

 Miiller, 1766, and Montfort, 1810, and therefore not to be accepted. 

 It is a member of the same genus as Bolten's Pterygia nucella accord- 

 ing to the consensus of authors. I therefore name the latter ( = Valuta 

 dactylus Linnaeus) as type of Pterygia^ of which C ylindromitra 

 Fischer, 1884, will be a synonym. In this way we may avoid the con- 

 fusion which the rejection of Marginella at the present day would 

 create, since there are few species of C ylindrannitra and they have 

 so far been the subjecct of very little publication. 



The species from the silex beds so far obtained all have the spire 

 exposed. Doubtless if the complete fauna was available we should 

 also find species of Persicula and Volvarina, as in most of our 

 tertiary faunas. 



MARGINELLA MOLLITOR, new species. 

 Plate 12, fig. 1. 



Shell small, smooth, solid, with about 4 whorls, which are ob- 

 scured by a continuous coat of enamel covering the spire ; last whorl 

 rather convex, the periphery at the shoulder terminating at the 

 aperture in a prominent wide, smooth varix, distinctly and sharply 

 separated b}^ a difference in level from the surface behind it, and 

 which also marginates the canal; aperture narrow; outer lip reced- 

 ing at the suture and canal, thick, having between the shoulder and 

 canal about 11 internal denticulations, or short lirae, which do not 

 enter the aperture beyond the varix ; body smooth, with a slight wash 

 of callus; pillar slightly concavely arcuate with four nearly equal 

 and equally spaced plaits, of which the anterior is at the edge of the 

 wide shallow and short canal. Length of shell 11.5, of apertures 

 7.5, maximum diameter 6 mm. 



Tampa silex beds at Ballast Point, Tampa Bay, Florida. 



Type specimen from the Post collection, U. S. Nat. Mus. No. 

 165058. 



MARGINELLA INFECTA, new species. 



Plate 12. fig. 3. 



Shell small, smooth, solid, of about 4 whorls, the spire being cov- 

 ered with a coat of enamel which obscured the suture and nucleus; 



