GUDE : ON NEW SPECIES OP PLECTOPYLIS. 217 



anterior extremity horizontal, then descends obliquely, and bifurcates 

 posteriorly ; fourth and fifth with the anterior extremity vertical, 

 descending obliquely in a curve, bifurcating posteriorly; sixth short, 

 oblique. Diam. maj. 11'5, min. 9"75 mm. ; alt. 4*5 mm. 



Hah. — Pac-Kha. Type in my collection. 



Larger specimens from the same habitat measure 12 mm. in diameter, 

 while others from Long-lluy (1,500 metres altitude) measure 10-5 mm. 

 in diameter. In addition to the differences already meutioned under 

 P. Gouldingi, the first palatal fold has a descending short ridge at its 

 posterior extremity, a feature absent in F. Gouldingi. 



Plectopylis fallax, n.sp. PI, IX, Fig. 6. 



Shell resembling P. Moellendorffi, but the spire is quite flat, and the 

 axis is relatively lower, the last whorl descends much more in front, 

 the aperture is more oblique and more dilated laterally. The anterior 

 parietal plate is shorter, leaving more space between it and the upper 

 and lower free horizontal folds, and it gives off, in addition, an anterior 

 and posterior ridge at the lower extremity ; the upper free horizontal 

 fold is also more produced ; the four inner palatal folds have their 

 posterior extremities also more horizontal than in P. Moellendorffi, 

 showing a tendency to bifurcation. Diam. maj. 17, min. 14-5 mm. ; 

 alt. 6"25 mm. 



Hah. — Muong-Bo. 



More variable in size than P. Moellendorffi,, the smallest specimen 

 measuring 13 "5 mm. in diameter. 



Var. MAJOE. 



This form has the aperture still more distended laterally, the 

 margins of the peristome more expanded, the last whorl more deflexed 

 in front, and the mouth more oblique. Diam. maj. 21, min. 17'5 mm. ; 

 alt. 8 mm. 



Hah. — Pac-Kha. 



At first I wasinclined to consider P. fallax a variety of P. Moellendorffi, 

 but, in addition to the deviations in the armature and other differences 

 indicated above, the shell has such a distinct facies that it seems better 

 to give it specific rank. 



Plectopylis cyrtochila, n.sp. PL IX, Pig. 5. 



Shell dextral, widely umbilicated, discoid, translucent, pale corneous, 

 smooth and polished especially below, finely irregularly striated. 

 Spire depressed, apex obtuse, suture deep. Whorls 6J, convex, 

 increasing slowly and regularly, rounded at the peripher)-, subangulated 

 round the wide, open, funnel-shaped umbilicus, last whorl slightly 

 deflexed in front, and slightly constricted behind the mouth. Aperture 

 roundly lunate, oblique, margins approaching ; pei'istome whitish, 

 a little thickened and slightly reflexed, the margins united by a slight 

 callus on the parietal wall, regularly curved. 



Parietal armature composed of two vertical plates, the anterior 

 slightly descending forward and thickened below, with a short support 

 on both sides of both extremities, those on the lower stout ; the 



