BY THE REV. J. E. TENISON-WOODS. 1055 



19. Clausilia, Drapaniaud, Hist. Nat. d. Moll, terrest. et fluv. 

 pp. 24, 29, 68. 



«S'/ie^Husiform, usually sinistral ; aperture elliptical or pyriform 

 with a posterior sinus contracted by lamellse closed when adult by 

 a moveable shelly plate (CZa2<5i7n<ni); peristome continuous, reflected. 



Animal with a short obtuse foot ; upper tentacles short, lower 

 small ; lung and reproductive orifices on the left side ; jaw finely 

 grooved. 



Radula like Helix, but both rows very numerous, sometimes as 

 many as 120 x 50. About 700 species, of world-wide distribution. 

 The peculiarity of the genus is the Clausilium, which is developed 

 in the adult state. The animal secretes an elastic calcareous 

 filament attached to the columella, round which it makes a half 

 turn. At the free end is a spoon-shaped lamina, smaller than the 

 aperture, but fitting it. Its elasticity enables the animal to push 

 it on one side when walking, and to use it as a door when within 

 the shell, securing it against intru.sion. 



Clausilia moluccensis, von Mart. Monatsber. Berl. Ak. 

 Apr. 1864, p. 270 ; {Phaedusa), Ostas. Zool. II. p. 381, pi. 22, 

 fig. 19 ; Pfr. Mon. Hel. VI. p! 412. 



Halmahera ; Ternate. 



Cl. penangensis (Phaedusa), Stol. Jour. As. Soc. Beng. 

 XLII. 1873, p. 27, pi. 3, figs. 4 6 ; Pfr. Mon. Hel. VIII. p. 465. 

 Penang Hill. 



Cl. sumatrana, von Mart. Monatsber. Berl. Ak. April, 1864, 

 p. 270 ; f Phaedusa), Ostas. Zool. II. p. 379, pi. 22, fig. 17 ; Pfr. 

 Mon. Hel. VI. p. 410. 



Sumatra. 



Cl. heldii, Kiist. p. 27, pi. 2, figs. 29-31 = Cl. javana, 

 Mon. Hel. II. p. 405. 

 Java. 



Pfr. 



