1882.] MOLLUSCAN FAUNA OF MADAGASCAR. 389 



The specimens from Madagascar agree exactly with a typical 

 example of this species purchased by the British Museum of Dr. 

 Krauss. The figure in the ' Conchylien-Cabinet ' appears to be 

 far more characteristic than that in Krauss's work. 



PisiDiuM JOHNsONi, sp. nov. (Plate XXII. figs. 28, 29.) 3 1\ '(^^Cf 



Shell minute, ventricose, inequilateral, glossy, finely concentrically 

 striated, pale grey. Umbones large, inflated, without'a small pointed 

 nucleus. Posterior side longer and narrower than the anterior, 

 obhquely sloping from the beaks, rounded at the extremity ; anterior 

 end broader, blunter. 



Length 2 millira., width 2^^, diam. \\. 



Hab. About 20 miles from Antananarivo (Johnson). 



This species is considerably hke P. ventricosum of Prime, but is not 

 not quite so swollen or so inequilateral. The beaks take the form of 

 an apical glossy cap without any small pointed apex. The ligament 

 is small and linear. 



EXPLANATION OF THE PLATES. 



Plate XXI. 



Fig. 1. Cyclostoma congener, p. 377. 



2. betsileoense, p. 376. 



3. , var., p. 377. 



4, 5. johnsoni, p. 378. 



6, 7. Vitrina madagascariensis, p. 379. 

 8, 9. Helix (Nanina) cleatnesi, p. 379. 



10, 11, 12. (Macrocgolis?) covani, p. 381. 



13, 14. {Helicophanta) hiGingulata, p. 380. 



Plate XXII. 



Figs. 1, 2, 3. Helix {Ampelita) shavi, p. 382. 



4. Bulimus (Bkachis) nigrilineafus, p. 382, 



5. Sfenogyra {Clavator) johnsoni, p. 382. 



6. Melanatria johnwni, p. 383. 



7. Ditto, lateral view of labrum. 



8, 9. Ampullaria madagascariensis, p. 384. 



10, 11. Cleopatra trahonjiensis, p. 384. 



12, 13. Limncea electa, p. 385. 



14, 15. Fhym lamellata, p. 386. 



16, 17. ohtusispira, p. 386. 



18, 19. madagascariensis, p. 386. 



20, 21, 22. Planorbis madagascariensis, p. 387. 



23, 24. Neritina fulgetrum, p. 387. K 



25, 26, 27. Corbicula madagascariensis, p. 388. 



28, 29. Pisidium johnsoni, p. 389. 



