Il6 GUDE : NEW AND UNFIGURED SPECIES OF PLECTOPVLIS. 



Aperture oblique obcordate. Peristome white, slightly thickened and 

 reflected ; the margins subparallel, united by a thin raised flexuous 

 ridge on the parietal wall, giving off a strong curved entering fold. 

 Parietal armature composed of two transverse plates, the posterior 

 crescent-shaped, deflected posteriorly below, a little thinner but longer 

 than the anterior, which is vertical, truncate above and triangularly 

 dilated below: above its upper extremity occurs a short, free, horizontal 

 fold and below the inferior extremity a longer, free, horizontal fold 

 reaching close to the posterior plate. -Palatal folds similar to those of 

 P. i^hhjaria, but the second is more attenuated and elongated anteri- 

 orly, and bifurcated posteriorly ; the third, fourth, and fifth folds are 

 less curved and more elongated, while the fifth is not bifurcated 

 posteriorly. 



Major diam. i6'75, minor 14; alt. 8 millim. 



Hah. — Than-Moi. 



The present species is nearly allied to P. pldyaria, but the shell is 

 larger and less depressed, the umbilicus deeper and more constricted, 

 the spiral ridges closer together and consequently more numerous, 

 and in addition it possesses half a whorl more. In the parietal arma- 

 ture P. moeUenilorffi differs from its ally in having the horizontal folds 

 above and below the anterior plate quite free. The differences in the 

 palatal armature are indicated in the diagnosis. 



The type, here figured, is in the collection of Dr.' von j\l Ollendorff. 

 Figs. 4a — 4c give three different views of the shell, fig. 4d the exterior 

 wall behind the peristome, while the parietal armature is shown in 

 fig. 4e, and the palatal armature in fig. 4f 



Pleetopylis (Endoplon) villedaryi, Ancey. Figs. 5a— 5^-. 



PJedopijUs villedariji, Ancey: Le Naturaliste, 18SS, p. 71, fig. 2. 



Pledopijli.^ (E/vJopIo/i) rlioanomphala, Mlklff. : Tom. cit., p. 75. 



Shell dextral, discoid, solid, deeply widely umbilicated, whitish- 

 corneous, finely striated and decussated with microscopic spiral lines. 

 Spire flattened, apex mucronate, suture impressed, ^^'horls 8, a little 

 rounded above, compressed at the sides, obsoletely angular at the 

 periphery, angulated above and keeled around the wide perspective 

 umbilicus ; increasing slowly and regularly, the last twice as round as 

 the penultimate, deeply and abruptly descending in front. Aperture 

 oblique, auriculate. Peristome strongly thickened and reflected ; 

 margins united by a strongly raised flexuous ridge, which gives off a 

 short oblique entering fold on the parietal wall. Parietal armature 

 composed of two strong oblique plates, the upper extremities inclined 

 towards the mouth the posterior longest; the anterior has the upper 



