AMPHIDROMUS, GROUP VI. 163 



The darker shells generally without black varices, and having a 

 small white basal patch ; all forms occurring either dextral or 

 sinistral. 



Length 54, diam. 28, longest axis of aperture 28 mill. 



Length 44, diam. 24, longest axis of aperture 24 mill. 



Bunguran, Natuna Islands (A. Everett). 



Amphidromus perversus SMITH, Ann. Mag. N. H. (6), 1894, xiii, 

 p. 457. A. perversus var. natunensis FULTON, Am. Mag. (6), xvii, 

 p. 69 (1896). (?) A. interruptus and A. chloris JACOBI. Archiv fur 

 Naturgeschichte, Ixi, 1895, p. 293, pi. 14 (1896), anatomy. 



There is no yellow girdle at the periphery, such as occurs in the 

 typical melanomma, though there is often a faint paler line, or a divi- 

 sion of the color, as in A. inversus. In some specimens, as fig. 88, the 

 white zone below the suture is nearly covered. This variety is ; re- 

 markably variable in color, size and shape, and varies from 6 to 7 

 whorls. It seems to me clearly related to aureus and mdanomma, 

 from which some specimens are to be distinguished only by the 

 locality. Many shells are perforate. 



The specimens figured are from Bunguran Island, received from 

 Mr. Fulton. 



The reference of A. chloris and A. interruptus of Jacobi to this 

 variety rests upon the locality of his material, as he gives no infor- 

 mation on the shells ; his interruptus being from the Natunas (Bun- 

 gimm), chloris from Djemadja, one of the Anubas (Anamba) group, 

 lying westward from the Natunas proper, and nearer the Malay 

 Peninsula. Jacobi gives full anatomical details, which show specific 

 differences from A. interruptus. 



Subsp. leucoxanthus (Martens). PI. 54, figs. 73-79. 



Shell ovate-elongate, striatulate, glossy; pale, greenish yellow 

 with a wide ivliite sutural band, with blackish-brown varices, usually 

 several in a group, whorls 7, but little convex ; suture deep, ap- 

 pressed. Aperture rounded, two-fifths to one-half the length of the 

 shell; peristome white, moderately thick, narrowly expanded, the 

 parietal callus white ; columellar margin nearly perpendicular. 

 Apex white (fig. 74) or black (var. oculata, fig. 73). (Martens.^ 



Length 49J, diam. 28^ mill.; length 41, diam. 24 mill. 



Length 51, diam. 27 mill.; length 37, diam. 22 mill. (var. oculata). 

 Siam : between, Chaniabun and Srakeo (Pavie). 



