— 355 — 



Pariétal armature (fig. 4'). composed of two vertical 

 plates, the posterior curved, obliquely desceading back- 

 wards, its upper extremity slightly reflexed ; anterior plate 

 very short, with a short horizontal fold some distance 

 above it and close to its lower extremity a longer horizont- 

 al fold, reaching nearly as far as the posterior plate. 



Palatal armature (fig. 4'), composed of six transverse 

 folds, the first low and short, the others semicircular, 

 more or less horizontal, and notched near their posterior 

 extremities, the fifth curved, having both its extremities 

 ascending; the second, third, fourth, and fifth are connec- 

 ted by a low vertical ridge which projects obliquely back- 

 wards below the fifth fold, giving the latter the appea- 

 rance of being bifurcated. 



Diam. maj. : 12,5; min. 11 mm. ; ait. 7 mm. 



Hab. : Quang Huyen, Tonkin. 



Type in the collection of the School of Mines, Paris. 



This and the next species belong to the section Sp'Acola. 

 P. suprafilaris difïers from P. infralevis in having a more 

 elevated spire, a narrower umbilicus, and a more rotundate 

 aperture, while the spirals are much coarser and descend 

 as far as the periphery. It dlRers also in the pariétal arma- 

 ture in Ihe anterior vertical plate and the horizontal folds 

 being much shorter, and in the posterior plate being more 

 oblique. In its palatal armature it resembles P. Muspratti 

 in having the four folds uiiited by a low vertical ridge 

 which projects obliquely below the fifth fold ; that species, 

 however, is sinistral. 



Plegtopylis soror n. sp, 



(PI. VII, fig. 10, H, 12) 



Testa prœcedenti similis, sed magis depressa superne et 

 latius umbilicata; anfr. ultimus supra peripheriam obtuse 

 angulatus, prope aperturam magis descendens ; striœ incre- 



