AMPHIDROMUS, GROUP XVIII. 221 



A. ADAMSI (Reeve). PI. 09, figs. 32-50 ; pi. 66, figs. 44, 4.',. 



Sliell ovate-conic, sinistral, imperl'orate, tliin, variously colored 

 (see below), but generally with a distinct t/dlinc or rtfldix/t border be- 

 low the suture, and a pink or purple umbilical area ; many forms with 

 yellow or reddish lands above and below the periphery. Glossy, 

 slightly striatulate, and showing excessively fine spiral stria- under a 

 lens, the apex punctulate. Whorls about 6, slightly convex, the last 

 rather swollen, aperture ovate, oblique, white or marked with dark 

 brown inside ; the peristome thin, expanded, white ; columella 

 usually carmine or purple, slender or straight, narrow below, 

 suddenly dilated and appressed above ; parietal callus a mere color- 

 less varnish. 



Islands on t/ie Borneo side of Balabac Strait, and N. Borneo. 



Biillmns adamsi REEVE, Conch. Icon. pi. 13, figs. 73 a, b, c, d 

 (June, 1848). ADAMS & REEVE, Zool. ' Samarang,' Moll., p. 58, 

 pi. 15, f. 1. PFR., Monogr. iv, 385 ; vi, 32 ; viii, 46 ; Conchyl. Cab., 



p. 89, pi. 31, f. 11, 12 MARTENS, Ostas. Landschn. p. 356, var. 



A and D; not the description. Bulitnus moniliferus GUI., PFR., 

 Monogr. Hi, p. 328 (exclusive of reference to Gould); not B. moni- 

 liferus Gld. Amphidromus adamsi Reeve, FULTON, Ann. Mag. N. 

 H. (6), xvii, p. 82, with varieties subunicolor " Martens," p. 5, f. 5; 

 articulata, pi. 5, f. 7 ; duplocincta, pi. 5. f. 4 ; luteofasciata, pi. 5, f. 

 2, 2 a; ornatn, pi. 5, f. 14 ; p. 83, var. rufocincta, pi. 5, f. 1 ; superba, 

 pi. 5, f. 10 ; simplex, pi. 5, f. 12 ; inornata, pi. 5, f. 6 ; afireocincta, 

 pi. 5, f. 3, 3 a (Jan. 1896). 



An extremely variable species, the limits of which may well be 

 amplified to include hamatus, placidus, angulatus and pictns as sub- 

 species. The forms from Banguey and an islet between that island 

 and Balambangan are merely color-phases of the typical form, similar 

 in rank to those of Liyuus fasciutus, described in Vol. XII of this 

 work, and deserving names neither more nor less than these. On 

 the mainland of Borneo a number of forms occur which may be con- 

 sidered either species or sub-species, at the option of the naturalist ; 

 for while their actual intergradation with typical adamsi may not as 

 yet be proven, the variation known renders it highly probable that 

 intergradation occurs. The species was named in honor of Arthur 

 Adams. 



Typical form. PI. 69, figs. 32, 33. Thin, smooth ; white or 

 grayish with three yellow bands, one below the suture, others above 



