48 GUDE : ON SOME KNOWN SPECIES OF PLECTOPYLIS. 



a. b. 



Fig. 2. — PlcdojnjUs scJdumbcrgeri. 

 a. Parietal armature. b. Palatal armature. 

 riedopylis sch lumber geri, as already stated,- is intermediate in size 

 between P. jovia and P. villedari/i, and the flexuous ridge on the 

 parietal callus is much more depressed. The figure of the anterior 

 view of the armature given by me in "Science Gossip," 1S97, N.S., 

 vol. iv, p. 138, copied froiii the Journal de Conchyliologie is un- 

 satisfactory, and I am pleased to be able to figure these structures 

 in situ. 



a. b. 



Fig. 3. — Plectojiylis villedaryi. 



a. Embryonic armature, 

 b. Palatal armature of mature shell. 



My specimen of P. villedanji, does not possess the upper denticle 

 in front of the parietal plate, shown in Mr. Pilsbry's figure in the 

 Manual of Conchology, 1893 (2), vol. viii, pi. 43, fig. 39, copied by me 

 i.e., p. 139, fig. 60b. 



My shell was found to contain two embryos. As no embryonal 

 armature had hitherto come under my observation, I was surprised to 

 find that even at this early age, the creature is provided with rudi- 

 mentary barriers. 1 have given a figure of the aperture of one of 

 these embryos (Fig. 3a.). 



The armature here simply consists of four short denticles : one on 

 the parietal wall, the other three on the outer wall — one above and 

 two below the periphery ; all four are situate at the aperture. 



Plectopylis lepida, Gude. 



Ann. and Mag. Nat. Hist., March, 1900 (s. 7), vol. v, p. 313. 

 Hah. — Tinh-Tuc, Tonkin. 



This species is now figured for the first time. The vertical 

 palatal folds overlap the parietal plate, leaving scarcely any room for 



