166 AMPHIDROMUS, GROUP VI. 



Mergui Archipelago ; and the dextral form seems to be the preva- 

 lent one. A single black varix on the ventral side of the last whorl 

 seems to be invariable, though it may not really be so. In one 

 specimen before me there is a distinct white sutural band, as in 

 leucoxanthm. The blackish parietal wall sometimes is overlaid with 

 a whitish layer. 



A. melanomma, natunensis, leucoxanthus.atricaUosus and aureus may 

 prove to insensibly grade into one another. The last name is prior. 



B. eques Pfr. is according to Fulton a decorticated specimen of 

 atricallosus. The description follows : Shell imperforate, ovate- 

 conic, solid, striate and obsoletely decussated with spiral striae, glossy, 

 white. Spire convexly conic, somewhat acuminate, whorls 6, a 

 little convex, the last a little shorter than the spire, slightly com- 

 pressed at the base. Columella rather straightened. Aperture 

 oblique, sinuate, half-oval ; peristorne white, the margins joined by 

 a deeply entering blackish chestnut callus ; right margin narrowly 

 expanded, columellar margin much dilated above, adnate. Length 

 48, diam. 23, aperture inside 22 mill. Cochin China, Mus. 

 Cuming. (Pfr.) 



A. DAUTZENBERGI Fulton. PI. 62, fig. 66. 



" Shell dextral, oblong-conic, very narrowly umbilicated, slightly 

 polished, of moderate solidity, whitish above, changing to greenish- 

 yellow below, obscurely spirally striated ; suture of last whorl 

 slightly impressed and bordered by a narrow white band ; whorls 

 6-^, the last obtusely angulated above the aperture at the periphery, 

 last half indistinctly malleated; aperture semi-oval, white within; 

 peristome moderately expanded, white, margins joined by a very thin 

 callus ; columella almost erect, rounded, widening at point of inser- 

 tion. Alt. 42, diam. maj. 21 mill." (Fulton.) Tonkin. 



A. dautzenbergi FULTON, Proc. Malac. Soc. Lond. iii, p. 303, fig. 

 Ill (October, 1899). 



'i A single specimen only of this distinct new form, received with 

 other shells from Tonkin. I have much pleasure in naming this 

 species in honor of M. Ph. Dautzenberg." (Fulton.) 



A. NIGROFILOSUS Rochebrune. 



Shell nearly covered, perforate, ovate-pyramidal, sinistral, obso- 

 letely striated, white, shining, obliquely painted with pale corneous 



