THE CYOLOPIiORID LAND MOLLUSSKS OF AMEKICA 175 



diameter, 13.9 mm.; lesser diameter, 9.8 mm. Height of aperture, 

 5.3 mm. ; diameter, 6.5 mm. 



This species is easily distinguished from the others by its small 

 size, weakly reflected peristome, and by the fact that notching of the 

 parietal wall is almost absent. 



BARBACYCLUS, new genus 



Amphicyclotine shells of helicoid shape, spirally banded. The 

 whorls are marked by oblique threads. The last whorl is very narrowly 

 solute and the outer lip at the posterior angle projects beyond the 

 junction with the parietal lip as a strong keel, which bends toward 

 the preceding turn and almost touches it. Operculum with the outer 

 edge of the turns provided with long scalelike fimbriations at the free 

 edge, which are longer than the width of the turns, forming the solid 

 portion of the operculum. The operculum therefore has a strongly 

 bearded appearance. 



Type: Barhacyclus underwoodi (Da Costa). 



Distribution : Costa Rica. 



B. dotocardi (Angas) has the radula formula 3 : 3 : 3 : 2, and the 

 jaw is without a median projection. 



KEY TO THE SPECIES OF BARBACYCLUS 



Last whorl strongly sculptured princeps 



Last whorl not strongly sculptured. 



Shell large; greater diameter more than 43 mm underwoodi 



Shell smaller; greater diameter less than 34 mm boucardi 



BARBACYLUS PRINCEPS (Pilsbry) 



Plate 23, Figukes 1-3 



1879. Cyclotus loucardi An gas, Proc. Zool. Soc. London, 1879, p. 483 (not C. 

 boucardi Angas, Proc. Zool. Soc. London, 1878, p. 73). 



1890. Cyclotus (?) boucardi yon 'Mastens (in part), Biologia Centrali-Americana, 

 p. 5. 



lOOO. Cyclotus boucardi von Mabtens, ibid., Suppl., p. 597. 



1935. Aperostoma (Aw,phicyclotus) princeps Pilsbby, Proc. Acad. Nat. Sci. Phil- 

 adelphia, vol. 87, p. 3, pi. 1, figs. 1, la, lb. 



Shell large, helicoid, of white ground color, marked with bands of 

 chestnut -brown. One of these bands, which is rather broad, appears 

 to occupy the middle of the turns; the other is immediately below 

 the periphery. Nuclear whorls 2, well rounded, smooth. Postnuclear 

 whorls well rounded, appressed at the summit, except the last turn, 

 marked by decidedly retractively slanting axial threads, which are 

 crossed by strong incremental lines. These threads begin a little ante- 

 rior to the summit of the turns and are about as wide as the spaces 



