Mascarene Lnnd-Mollusca. 429 



Erepta {lyupontia) perlucida, H. Adams. 

 (PI. X. tig. 5, shell ; PL XI. figs. 1-1 d, animal.) 



Macrochlamys iu nomenclature. 



Locality. Mauritius {E. Dupont). 



Shell very depressedly globose, of thin texture^ umbili- 

 cated, base flat ; sculpture quite smooth, glassy to the eye, 

 except on the apical whorls, where longitudinal striation is 

 very well seen ; colour pale greenish ochre ; spire very low, 

 sides flat, apex rounded ; suture very shallow ; whorls 5, 

 regularly increasing, very flattened, the last rounded on the 

 periphery; aperture lunate, oblique ; peristome very thin, 

 coluraellar margin, oblique, not reflected and only slightly 

 thickened. 



Size : major diam. 9"25, alt. axis 3*5 mm. 



Animal black ; the wall of the branchial cavity is mottled 

 black and white, the former predominating. The foot is 

 divided and has a broad peripodial margin marked with 

 black, and the sides of the foot are mottled with grey. The 

 left shell-lobe is narrow and long, widest in the middle part, 

 tapering away on both sides. The left dorsal lobe is in two 

 distinct parts, contiguous to each other. The visceral sac is 

 brown on the apical whorls. 



The teeth of the radula are like those of levis. Formula : 



39 . 1 . 8 . 1 . 8 . 1 . 39, or 48 . 1 . 48 



The central and admedians have broad squarish plates, the 

 teeth broad and blunt with no side cusps, narrowing, but still 

 bluntly rounded, up to the 11th and 12th transition teeth. 

 On the 13th tooth a small notch occurs very low down on 

 the outside; this notch rises gradually upwards to the 19th 

 tooth and theuce to the margin all are evenly bicuspid. 

 Jaw with a concave cutting-edge, centre part nearly 

 straight. 



Generative organs. No amatorial organ. The penis, com- 

 mencing at the generative aperture, is cylindrical and elongate 

 to where a small accessory sac is given ott', the portion next 

 above this tapers gradually to the retractor muscle ; the 

 cpiphallus is short and is the seat of the spermatophore up 

 to where the vas deferens unites with the penis, there is at 

 this point a long thin flagellum. The spermatheca is a long 

 narrow tube, terminating probably in a bulb ; just above 

 its junction with the free oviduct there is a large globose 

 swellmg in this duct, which narrows suddenly again towards 

 the oviduct and where the vas deferens commences. 



