igiS-] O. K. GuDE : Mollusca, IV. 511 



Type No. 3584 Brit. Mus. 



This new species is evidently related by its palatal armature 

 to P. brahma, these barriers being even more complicated than 

 in the latter form. In its simple parietal armature, however, it 

 stands rather isolated in the group, coming nearest to P. oglei, 

 but that shell is much larger and is dextral. The species is asso- 

 ciated with the name of Captain Bedford, who appears to have 

 been the first officer to go into that part of Assam, viz. in 1826. 



Plectopylis (Endoplon) aborcnsis (G.A, MS.j, sp. n. 

 (PI. xlii, figs. 3, 3a, 36, 3c, 3d). 



Shell sinistral, solid, stoutly discoid, ochraceous, with a deci- 

 duous cuticle, widely openly umbilicated, finely and rather regu- 

 larly striated, dull, the protoconch glossy and rather distantly 

 faintly ribbed. Whorls 6J, closely coiled, increasing slowly and 

 regularly, the last a little dilated towards the mouth, deeply des- 

 cending in front, the upper side flattened, bluntly keeled above, 

 the keel disappearing near the aperture, convex at the side, angu- 

 lated around the umbilicus, spire sunken, but the upper side of the 

 wliorls horizontal, not sloping, so that the whorls are terraced ; 

 suture impressed above, but channelled in the umbilicus ; apex a 

 little raised, being about on a level with the outer whorl. Aper- 

 ture nearly horizontal, broadly lunate; peristome thickened and 

 reflexed, the margins united by a slight raised ridge on the 

 parietal wall, notched at the junctions with the peristome above 

 and below; upper margin slightly ascending, outer depressed at 

 first, basal arcuate, columellar ascending and slightly impinging 

 upon the umbilicus. 



Parietal armature consisting of: 1°, a transverse plate, ob- 

 liquley curving downwards and backwards, with a short posterior 

 support at the upper extremity, where it gives off anteriorly a 

 horizontal fold, running parallel with the upper suture; 2°, a 

 much shorter vertical plate, placed anteriorly to the first, its 

 lower extremity having a short support on either side, its upper 

 extremity simple and terminating about the periphery ; a very 

 slender fold rises some distance behind the first plate, running 

 close to and parallel with the lower suture, joining the parietal 

 ridge at the aperture. The palatal armature consists of five folds • 

 the first, near the upper suture, slight and obliquely descending 

 backwards ; the next three transverse, very stout, short, elevated, 

 and rather square in outline, the second having a short obliquely 

 ascending support at its upper, and an obliquely descending one 

 at its lower extremity ; the third and fourth with a short support 

 anteriorly above and below, giving that side a concave appearance, 

 and posteriorly with a short obliquely descending support at its 

 lower extremity; the fifth is near the lower suture, slight and 

 horizontal, a little stouter and more elevated than the first. 



Major diam. 14, minor 11 "5 mm. ; alt, 6"5 mm. 



