1918.] H. H. Godwin-Austen : Mollusca, VIII. 595 



Oxytcs aborcnsis, n. sp. 

 (Plate Hi, figs. 2, 2a, 2b.) 



Locality. — Between Silli and Dukku, Yamne Valley, 2000 ft.; 

 Rotung, No. 3121 B.M. coll., young, with 5 whorls {Capt. G. F. T. 

 Oakes, R.E.). 



Shell very depressedly lenticular, more convex below than 

 above, openly umbilicated, fragile, very sharply keeled; sculpture 

 very finely and closely decussate, oblique to the whorl; colour 

 rich ochraceous; spire very flatly conoid, apex flatly rounded; 

 suture linear; whorls 6, regularly increasing; aperture oblique, 

 semilunate , upper margin sinuate and descending ; peristome thin ; 

 columellar margin sub vertical. 



Size: maj. diam. 3i'25, minor 27*0, alt. axis 7*0 mm. 



24-0, „ 2075 ,, ,, 6-0 ,, (small 

 var. of 5 whorls). 



This species (all immature) was also collected by Captain 

 Oakes at the furthest point he reached on the Dihang R. (Siang of 

 the Abors) near where the Sigon R. joins it, and between Long. 

 94°55' and 95°i5' and Lat. 29° and 29°i5'. The keel is slightly 

 compressed on both sides and the shell is duller in colour. 



This species recalls 0. blanfordi, Th. from Darjiling, but the 

 umbilicus is much wider and open and the sculpture is finer in the 

 Abor shelLs. 



In general form it is similar to 0. pollux of the Khasi Hills, 

 but openly umbilicated. It is very close to 0. shanen^is, G.-A., 

 of the Shan States, types in the Blanford collection (36.06.3.3 

 B.M. coll.), collected by Mr. Feddon of the Geological Society. 

 The Abor shell is more openly umbilicated, sharper keeled and the 

 sinuate margin of the peristome between suture and keel is very 

 distinctive. 



Oxytcs siyomensis, n. sp. 



(Plate lii, figs. 3, 3a, 3&.) 



Locality. — Siyom Valley, Abor Hills (Long. 94"^ 40' and Lat. 

 28° 30') high up [Capt. Oakes, R.E.). 



Shell openly perspectively umbilicated, rather solid, lenticu- 

 lar depressed, sharply keeled; sculpture fine close transverse stria- 

 tion, on base close pitting; colour bleached in type, pale umber in 

 a second specimen; spire fairly high, apex rounded, sides flatly 

 convex; suture linear; whorls 5, regularly increasing; aperture 

 semilunate, subvertical; peristome: upper margin sinuate, com- 

 pressed towards keel so as to be concave, lower margin oblique. 



Size: major diameter 25*0, minor 21-5, alt. axis 7-0 mm. 



This differs from aborensis, a close ally, in being more solid 

 and not so extremely flat. A smaller specimen from the same 

 valley has the peristome much thickened. Major diam. 24*0, alt, 

 axis 68 mm. 



