THE NAUTILUS. 65 



I. Peristome continuous, free, or continued as a thick cord across 



the parietal wall ; aperture subtriangular, squarish or subcircu- 

 lar, the throat with two or three plicae. 



Genus MOELLENDORFFIA Anc. 



1. Apical whorl granulated ; parietal callus free and erect or 



shortly adnate. 



a. Spire convex or low-conic ; surface coarsely warty ; peri- 

 phery angular or rounded, both sulci below it ; peristome 

 continuous, the parietal callus free and erect, bearing a 

 rounded tooth. There is often a small sulcus above the 

 principal outer one. 



Subgenus Moellendorffia s. str., Anc. 



a 1 . Spire flat, the periphery carinate, two sulci, one subperi- 

 pheral, the other basal below it. Aperture subcircular, 

 the adnate parietal callus very short, not toothed. 



Subgenus Moellendorffiella Pils. 



2. Apical whorl smooth ; parietal callus adnate, thickened at the 



edge ; spire more or less concave ; aperture heart-shaped, 

 subtriangular or squarish ; edge of the parietal callus thick- 

 ened, cord -like. Surface minutely granose between larger 

 warts which sometimes bear hairs. Typically with a basal 

 and a superperipheral furrow behind the aperture, with cor- 

 responding prominences inside, but these may be reduced to 

 indistinct vestiges. Subgenus Trihelix Anc. 



II. Peristome widely interrupted, the parietal callus thin through- 



out ; aperture rounded-lunate ; periphery rounded and spire 



convex in known forms ; apical whorl smooth. 



a. Sinistral, last whorl distorted ; external sulci vestigeal ; no 



internal lamellae. Genus STEGODERA Martens. 



a 1 . Dextral, regular ; three external sulci and internal plicse. 



Subgenus Traumatophora Anc. 

 The species now known are as follows : 

 Moellendorffia eastlakeana (Mlldff.), China. 

 Moellendorffia hensaniensis (Gredl.), China. 

 Moellendorffia trisinuata (Marts.), China. 



Moellendorffia trisinuata sculptilis (Mlldff.), China. (PI. 2, figs. 

 7,8.) 



Moellendorffia loxotata (Mab.). Tonquin. 

 Moellendorffia spurca (Bav. & Dautz.). Indo-China. 



