CENTRAL PKOVINCE SPECIES. 171 



figure) very low, wide, with one inner, long, blunt cutting point, and 

 one outer, small, blunt. Tbe low, wide marginal teeth of this species 

 are peculiar. 



SPURIOUS SPECIES OF MICROPHYSA. 



Microphysa mlnuscula of Von Martens (Alb., eel. 2) is a Zonites (q. v), 



POLYGYRErLA, Bland. 



Animal heliciform ; mantle subceutral ; other characters as in Pa- 

 tula. 



Shell widely umbilicated, discoidal, ribbed above, smoother below ; 

 whorls 7-8, gradually increasing, the last fio. igi. 



deflected above, furnished within with two 

 rows of three teeth ; base flattened ; um- 

 bilicus of equal size to the apex ; aperture 



subvertical, oblique, lunate-oval 5 peri- jn^ oiP.iwiygyreUa. 



stome white, simple, much thickened within, margins joined by a white, 

 jiliciform, elevated, triangular tooth. 



Central Province ; a single species known. 



Jaw of the onlj' known species, P. poJygyrella, very low, wide, very 

 slightly arcuate, ends very gradually attenuated ; cutting margin with- 

 out median projection ; anterior surface with numerous (even 20) 

 broad, slightly separated ribs, denticulatiug either margin. 



Lingual membrane (Terr. Moll., V, Plate VII, Fig. A) long and nar- 

 row. Teeth 27-1-27, with 5 perfect laterals. Centrals sub(iuadrate, 

 the lower lateral angles but little exi)anded, the upper margin broadly 

 reflected ; reflection large, wide, with distinct but small, rounded side 

 cusps, bearing short conical cutting points, and a very stout median 

 cusp, reaching the lower margin of the base of attachment, beyond 

 which projects the short, stout, conical cutting point. Laterals like 

 the centrals, but asymmetrical by the suppression of the inner, lower 

 angle of the base of attachment and the inner side cusp and cutting 

 point. First marginals a simple modification of the laterals by the 

 lesser development of the cutting point {h). Outer marginals (c) low, 

 wide, the reflection equaling the base of attachment and bearing one 

 inner, short, stout, oblique cutting point, and two shorter, outer, blunt 

 cutting points. 



Polygyrella is quite distinct from all the other American genera by 

 the form of its jaw and the large number of ribs upon its anterior sur- 

 face, 



