PERUSSACIA OF MAURITIUS. 233 



Species of Mauritius. 



16. F. BARCLAYI (Pfeiffer). PI. 42, figs. 66, 67, 70, 71. 



Shell oblong, thin, smooth, corneous; spire convexly conic, 

 the apex rather acute ; suture shallow, simple. Whorls 5, a 

 little convex, the penultimate large, last whorl a little shorter 

 than the spire, slightly tapering at the base. Aperture ver- 

 tical acuminate-oblong; columella oblique and lightly twice- 

 twisted ; peristome simple, unexpanded, the right margin sinu- 

 ate above, subangularly arched forward in the middle. 

 Length 9, diam. 4, aperture 4.5 x 2 mm. (Pfr.). 



Mauritius (Isle of France), Sir D. Barclay in Cuming coll.; 

 Mt. Oriz and Moka, G. Nevill. 



Spiraxis barclayi PFR., Proc. Zool. Soc. 1855, p. 99 ; Monogr. 

 iv, 580; vi, 197. Cionella &., MARTENS in Mobius, Reise nach 

 Mauritius, p. 199. Ferussacia &., NEVILL, Handlist Moll. 

 Indian Mus. i, p. 161. Glandina vesiculata, Benson, SEMPER, 

 Risen im Archipel Phil., Landmoll. p. 135 (jaw and teeth). 



"Only distinguished from its European close ally, F. folli- 

 culus, by the more turrid last whorl and broader aperture. It 

 lives gregariously under large blocks of stone. The animal is 

 bright yellow and very active. A single one of the living 

 specimens which I found was reversed." (G. Nevill). 



The shell is composed of 5y 2 whorls, which increase regu- 

 larly and very slowly to the penultimate. Here the suture 

 descends much faster so that the penultimate whorl widens 

 rapidly. The whitish sutural border is more conspicuous than 

 the figures indicate. A slightly convex, calcareous, white 

 epiphragm guards the dormant snail, as shown in fig. 71. 

 Specimens measure 



Length 8.6, diam. 3.5, length aperture 4 mm. 



Length 10, diam. 4, length aperture 4.5 mm. 



Length 8.3, diam. 3.5, length aperture 4 mm. 



I am much inclined to believe that this species is an im- 

 portation from southern France. It would otherwise be very 

 difficult to account for its occurrence in Mauritius. 



Semper has examined the mouth-parts of specimens sup- 

 plied by G. Nevill. The ja.w has at least 20 fine riblets; radula 



