— 346 — 



extract the insect it was damaged, so that I was unable to 

 recognizeitsorder with certainty, butsufficiently remained 

 to lead me to think it was the larva of some minute Coleo- 

 pteron. It measured 1,23 mm. in length. Some information 

 on the subject of attacks by predatory insects and other 

 animais on moUuscs may be found in a paper of mine in 

 Science Gossip, New Séries, vol. III, 1896, p. 88. 



Plectopylis Giardi h. Fischer 



H. Fischer, Bull. Scient. France et Belg., XXVIII (1898), p. 320, 

 PI. XVII, fig. 17-21. 



GuDE, Science Gossip N. S., vol. V (1899), p. 332, fig. 95. Ibid., vol. VI 

 (1899), p. 76, fig. 103. 



Cao Bang (Billet), Quang-Huyen (Mansuy). 



A considérable séries of spécimens of Ihis species was 

 received, presentingsome variation in size, the smaller spé- 

 cimens ranging from 13 to 17 mm. in diameter. Thisform 

 may be designatedas var. minor. The larger shells measure 

 from 19 to 23 mm. in diameter. In several of the smaller 

 spécimens a double séries of palatal folds was visible 

 through the shell wall, and thinking that thèse shells 

 might difler from P. Giardi I opened a couple of spéci- 

 mens, and I was surprised to find a complète séries of new 

 barriers close to a partially absorbed older séries, the two 

 séries of pariétal barriers being, in fact, superimposed. 

 Behind the anterior verti(;il plate, but in front of the pos- 

 terior one was a low parallel ridge, the remains of the 

 préviens anterior plate ; while behind the posterior plate 

 was the partly absorbed, posterior plate of the older séries 

 (seefig. l*')(l).Of the palatal armature only the bases of the 

 older séries could be discerned, their absorption being in 

 a much more advanced state. An analogous case was observ- 



(1) Les figures insérées dans le texte ont été clichées d'après les 

 dessins originaux de l'auteur. 



N. D. L. R. 



