AMPHIDRUMUS, GROUP VI. 159 



In the wide white sutural band it approaches A. leucoxanthus ; in 

 the short, obese shape, A. interruptus; but it is more solid, with 

 more convex whorls, much more widely reflexed peristome and 

 entirely diverse color and pattern. The original specimens _were 

 sinistral, but Mr. Everett collected dextral examples also, one of 

 which has been figured by Mr. Fulton. It is named in honor of 

 Prof. E. von Martens. 



6. Group of A. aureus. 



Includes forms allied to A. perversus, living on the mainland of 

 southeastern Asia, the Malay Peninsula, and various islands as far 

 south as Sunda Strait. Most of the species are more or less concave 

 below the suture, and in only one (doh-rni), is the lip completely 

 adnate behind, as in perversus ; some others having it imperfectly 

 adnate, while in most it is merely reflexed or recurved. The follow- 

 ing key is artificial and merely a temporary expedient. 



a. Shell with a very oblique, strong, white, raised varix on the back. 



Annam. costifer, p 17G. 



a 1 . Shell solid, large, alt. 64-70 mm., with three elevated girdles. 



Annam. ingenj, p. 175. 



a 2 . Without such sculpture. 



b. Uniform or nearly uniform yellow, white or greenish ; 

 lip not adnate behind. 



c. Pale yellow, somewhat cylindrically elongate, 



peristome narrowly expanded ; alt. 39, diam. 



17 mm. cochinckinensis, p. 118. 



c 1 . White or yellow, more conic, the diam. more than 



half the alt. Annam. metablelus, p. 174. 



c 2 . White, obese ovate, imperforate, the lip narrowly 



reflexed. mundus, p. 174. 



c 3 . Whitish above, greenish-yellow below, last whorl 



obtusely angular in front, parietal callus thin ; 



alt. 42, diam. 21 mm. Tonquin. 



dautzenbergi, p. 166. 



b l . Shell yellow, often with white band below suture, and 

 blackish varices ; lip recurved. 



c. parietal wall white. leucoxanthus, p. 163. 



c 1 . parietal wall blackish-brown, a solitary blackish 



varix. btricallosus, p. 165 



