202 BOYSIDIA. 



irregular growth striae. Last whorl laterally compressed, and 

 strongly ascending in front. Aperture vertical, subquadrate, 

 the margins moderately expanded, converging and joined by 

 an adnate callous. Columella very oblique. Lip parallel to 

 the columella; basal margin arcuate. Two parietal lamellae, 

 the upper one marginal, lamellif onn, deeply entering and giv- 

 ing off a triangular, dextrally incurved denticle ; the inferior 

 lamella weak and deeply immersed. Columellar lamella sub- 

 marginal, deeply entering and twisted. Three palatal plicae, 

 the upper strong, marginal, and then forming in the throat a 

 plate almost reaching the parietal fold ; middle one rather 

 strong; lowrr weak, and both deeply immersed. Color pale 

 tawny, peristome and teeth white. Alt. 5, greatest diameter 

 314 mm.; aperture 2% mm. high, 2 mm. wide (B. & D.). 



Indo-China: Phong-Tho (Messager). 



Boysidia robusta B. et D., Journ. de Conchy!., 1912, p. 18. 

 pi. 3, f. 1-3. 



The largest of its group. The angular lamella is high, 

 arcuate, its inner end curving towards the upper palatal 

 plica, and united by a lower callous to the long, deeply enter- 

 ing parietal lamella. The infraparietal is also long, entering 

 deeply. The columellar lamella is long, straight, and descends 

 inwardly. The upper palatal plica arises just inward from the 

 boss on the lip defining the sinulus, and descends inwardly. 



7. BOYSIDIA LAMOTHEI Bav. et Dautz. PI. 35, figs. 3-6. 



The shell is thin but opaque, turbinate, narrowly perforate. 

 Spire pyramidal, the apex rather obtuse. Whorls 5, convex, 

 gradate, joined by a conspicuous suture, nearly smooth, even 

 under a lens showing only inconspicuous growth-striae on the 

 later whorls. Last whorl rounded, ascending at the end. 

 Aperture vertical, subquadrate, having many folds, the peri- 

 stome thickened and dilated, the margins joined by a very 

 thin, glossy and moderately expanded callous. Three parietal 

 lamellae, the upper lamella marginal, very strong and, with 

 the upper palatal plica, forming a rounded sinulus; middle 

 lamella immersed and lamellif orm; lower lamella weak and 

 deeply immersed. Columellar lamella strong. Palatal plicae 



