AMFHIDROMUS, GROUP XVIII. 219 



Monogr., vi, p. 27. SCIIEPMAN in Veth's Midden Sumatra, Moll., 



p. 8 (1880) A. sumatranus Mart., FULTON, t. c., p. 88 (1896). 



DAUTZENBERG, Ann. Soc. Roy. Malac. Belg., xxxiv, p. 6, pi. 1, f. 2, 



2 a (1899) '! Bulimus (Amphidromus} adamsi Reeve, BOCK, P. Z. 



S., 1881, p. G30. 



The shell is smoother and more glossy than other members of the 

 group, the last whorl bluntly angular. The upper two-thirds of the 

 last whorl, and the visible portion of the preceding whorls, is yellow- 

 ish gray-white, with one or two white bands with regularly spaced 

 brown spots ; the upper band (sometimes absent) runs below the pre- 

 ceding suture, the lower close above the following suture and at the 

 periphery of the last whorl ; and besides there are pale grayish 

 nebulous streaks, forked above (y-like), and ending below in the 

 spots of the lower band. If these cloudy markings were brown, the 

 pattern would resemble that of A- fnrciUatus. At the base of the 

 last whorl there are three narrow blackish spiral bands, the space be- 

 tween the first and second yellowish brown, that between the second 

 and third whitish yellow. The third band frequently is lighter, even 

 green ; and the umbilical tract defined by it is not roseate, but of a 

 greenish-yellow color, darker than the rest of the shell. 



It is likely that the shells collected by Mr. C. Bock at Sidjoend- 

 joeng, Paio, etc., in the Padang district, and identified as A. adamsi, 

 were really A. sumatranus, but no details of color, etc., are given. 

 See under A. adamsi var. pictus. 



A. SEMIFRENATUS Martens. 



A peculiar form, between porcellanus and sumatranus, having the 

 slender contour in common with the former, and in a few specimens 

 the two wide brown bands on the base ; but the upper surface of the 

 last whorl and the visible part of those preceding is more similar to 

 sumatranus, being pale greenish or bluish white, with small pale 

 brown spots in one or two spiral rows. The last whorl is more yel- 

 low throughout than in the two species named, and the brown bands 

 may vanish to a greater or less extent, but in that case there still re- 

 mains of the lower one a narrow black-brown bandlet which winds 

 around the insertion of the columella, and is continued on the outer side 

 of the peristome to the middle of its height. A few examples are other- 

 wise quite uniform yellow, but show this dark brown columellar band- 

 let and this dark brown streak behind the reflection of the white per- 



