HELIX. 85 



but slightly so ; last volution acutely carinate at the middle, and 

 convexly flattened beneath. Aperture small, oblique. Peristome 

 thin, outer margin above the keel scarcely expanded, beneath it 

 feebly thickened and narrowly reflexed, in the umbilical region 

 more expanded and partly concealing the perforation. 



Length from 10 to 11 mill., greatest diameter of base also 10- 

 11 mill. (Bock.) 



Paio, Sumatra; in the forests, 1500 feet above the sea. 



H. (Geotrochus) rufo-filosa BOCK, P. Z. S. 1881, p. 630, t. 55, f. 4. 



H. NIAHENSIS God win- Austin. PL 18, fig. 66. 



Shell dextral, pyramidal, thin texture, base flat ; sculpture, spiral 

 lirse, fine, regular, not of continuous thickness, crossed by lines of 

 growth ; color white, with some fine marbling in a greyer color, 

 within the aperture porcellaneous white ; spire high, pyramidal, 

 sides slightly concave ; apex acuminate ; suture fine, linear ; whorls 

 7, very flat; aperture ovate, wide and ample, oblique; peristome 

 sharp, coming. to an angulate form at the outer keeled margin, ex- 

 panded and thickened below towards the columellar side. 



Size: maj. diam. 18'8, min. 16'0; alt. axis 12'3 mill. (G. Aust.) 



Niah Hills. 



H. (Geotrochus) niahensis AUST., P. Z. S. 1891, p. 44, t. 2, f. 3. 



Described from a single specimen. 



H. TIG^ENSIS Godwin-Austin. PI. 18, fig. 65. 



Shell pyramidal, rounded below, narrowly umbilicated ; sculpture, 

 irregular transverse lines of growth, indistinct concentric striation on 

 base ; color very pale ochre throughout ; spire pyramidal, sides flat ; 

 apex blunt ; suture linear ; whorls 6, very flat ; aperture semi- 

 lunate ; peristome reflected upon the columellar margin, which is 

 very oblique. 



Size: maj. diam. 9-3 ; alt. axis 8'0 mill. (G. Aust.) 



Tiga Island, Borneo. 



H. (Geotrochus) tigcensis AUST., P. Z. S. 1891, p. 44, t. 2, f. 5. 



Described from a single specimen. 



H. SUBFLAVA Godwin-Austin. PL 18, fig. 52. 



Shell pyramidal, keeled, rather flat on the base, narrowly per- 

 forate ; sculpture, rough pappillate dottings arranged transversely ; 

 color ochre ; spire high, sides flat ; apex very blunt ; suture linear ; 



