Species of Amphidromus, Aiders. 71 



absent, the specimens being of a uniform yellow colour, with 

 a narrow white band at the suture. 



6. A. enganoensis, Fulton. (PI. VI. fig. 11.) 



Loc. Engano Island, W. Sumatra (Dr. O. Modigliani). 



Shell sinistral, oblong-ovate, perforate, solid, shining, 

 obliquely striate ; ground-colour either yellow or rich brown, 

 sometimes in the latter case with two or three darker brown 

 spiral bands ; whorls 7, convex, suture strongly impressed with 

 a spiral narrow white band ; lip and columella broadly ex- 

 panded and slightly reflected, margins joined by a thin trans- 

 parent callus, columella more or less deflected at point of 

 insertion. 



Long. 49 millim., maj. diam. 28 millim. (brown specimen 

 n my own collection). 



Long. 49 millim., maj. diam. 27 millim. (yellow specimen 

 in my own collection). 



Long. 49 millim., maj. diam. 27 millim. (banded specimen 

 in Col. Beddome's collection). 



This species is in form like a large janus, but easily dis- 

 tinguished by its broadly expanded lip and columella, its 

 different coloration, and the absence of the dark colour on 

 parietal wall. 



7. A. Martensi, Boettger, Nach. malak. zool. Gesell. 1894, 



p. 66. (PI. VII. fig. 10.) 



Loc. Kina Balu, N. Borneo (Everett) . 

 A distinct and handsome species, occurring both dextral 

 and sinistral. 



8. A. mundus, Zeit. fiir Malak. 1853, p. 57; Ckem. ed. ii. 



pi. lxx. figs. 21, 22. 



This may possibly be but a variety of perversus, but all 

 the specimens I have seen appear to be different in form as 

 well as in colour. There are two very large specimens in the 

 British Museum, similar in size and form of aperture to 

 typical atricallosus, but in other respects like mundus. 



Group of A. comes. 



9. A. polymorphus, Tapparone Canefri, Make, de viaggo del 



Magenta, 1894, p. 82, pi. ii. figs. 4 a and b. 



Loc. Cochin China. 



In most collections this appears as a variety of perversus ; 

 but it is quite as worthy of specific rank as inversus and 



