106 WEST AFRICAN GLESSULA. 



86. G. DEALBEBTISI Pollonera. 



Shell oblong-subsubulate, very clear and translucent, am- 

 ber-greenish, very finely striatulate longitudinally. Spire 

 turrite, the apex obtuse ; whorls 7, a little convex, parted by 

 an impressed suture. Aperture oblong-piriform, acutely 

 angular above, not differently colored within; peristome sim- 

 ple, thin; columellar margin arcuate, obliquely truncate. 

 Length 18, diam. 5.5, aperture 6.5 mm. long. (Poll.). 



East Africa : Bihunga, Ruwenzori ; Valle Mobuku, at about 

 2500 meters elevation, one example (Luigi, Duke of Abruzzi). 



Glessula De-Albertisi POLL., Bolletino dei Mus. di Zool. 

 ed Anat. eomp. della R. Univ. di Torino, No. 338, vol. xxi, 

 p. 2, October, 1906. 



VII. West African species. 



Two quite distinct groups of Glessula are represented in 

 West Africa. The group of G. lavigata, has substantially 

 the shell-structure of Indian Glessulae. The shell is smooth 

 throughout (species 87, 88) . In the group of G. paritura the 

 post-embryonic whorls are finely rib-striate (species 89 to 92). 



Group of G. lavigata. 



The central teeth of G. lavigata are narrow, not half as 

 wide as the adjacent laterals. There is a well developed 

 but not overhanging cusp. The laterals are quadrate, tricus- 

 pid, with overhanging cutting-points on all the cusps. Middle 

 cusp longer than the basal plates. There are about 8 laterals, 

 then one or two transitional teeth, followed by the marginals, 

 also of the tricuspid type (pi. 15, fig. 9). The jaw (pi. 15, 

 fig. 10) is very minutely plaited, serrate on the cutting edge, 

 at least in places. 



87. G. LJEVIGATA (Pfeiffer). PL 14, figs. 9, 11, 12. 



Shell turrite-oblong, rather solid, smooth, buff- waxen ; spire 

 elongated, the apex obtuse. Whorls 6, but slightly convex, 

 the last about one-third the total length, rounded beneath, 

 striolate anteriorly. Columella callous, somewhat twisted, 



