PLECTOPYLIS. 157 



plate, the convexity of the curve outward, the upper border of it 

 slightly scalloped ; a minute denticle stands in front of the lower end 

 of this plate. The outer wall bears 7 plicse, the two outer small, 

 parallel to the sutures, the next to the lowest fold very minute, situ- 

 ated somewhat back of the others; the four median larger, and 

 directed obliquely across the whorl. 



Alt. 13, diam. 29-31 mill. 



Near Halong, Tonquin. 



Plectopylis jovia MAB., Bull. Soc. Mai. Fr. 1887, p. 99. 



This species, of wjhich part of the original lot collected by the 

 Abbe Vathelet, is before me, is allied to P. schlumbergeri, differing 

 mainly in the more elevated parietal callus and larger size. 



It is not improbable that both jovia and villedaryi will prove to 

 be varietal forms of schlumbergi. 



P. VILLEDARYI Ancey. PL 43, figs. 36, 37, 38, 39. 



Shell depressed, the spire nearly plane; umbilicus regular, brofid, 

 its width contained about 2-1 times in the greatest diameter of the 

 shell ; solid, opaque, striated. k 



Whorls 6i, very slowly widening, the last descending in front, 

 very convex^ almost angular around the umbilicus. Aperture 

 oblique, obstructed by an elevated tongue-shaped callus connecting 

 the ends of the peristome, which is very heavily thickened and 

 strongly reflexed. A stout lamella arises from the middle of the 

 parietal callus and extends obliquely into the mouth, being about 

 4-5 mill. long. One-third of a whorl inward the throat is obstructed 

 by a transverse septum on the parietal wall, in front of each end of 

 which there is a small tubercle, the upper -ene smaller, the lower 

 elongated ; on the outer wall there are 7 short plicse, the "two outer 

 ones minute, parallel with the sutures, the lowermost separated from 

 the next visible fold by a rather wide space, in which when closely 

 examined a more minute fold is seen, situated to the rear of the 

 others ; the rest of the folds are larger, obliquely placed. 



Alt. 9, diam. 20 mill. 



Region of Lang-son, and Bac-ninh, Tonquin. 



Plectopylis villedaryi ANC., Le Naturaliste, March, 1888, p. 71, 

 fig. 2. 



Differs from the schlumbergeri chiefly in the smaller size and more 

 elevated parietal callus. It is also closely allied to jovia, but a 

 close examination shows certain differences, such as the* presence of 



