AMPHIDROMUS, GROUP VI. 161 



his first voyage. Landing for water and wood at Prince Island, as 

 they were leaving Sunda Strait, some lofty trees were felled by the 

 sailors, and these shells were found among the foliage. The speci- 

 mens figured by Martyn and Donovan (and therefore my copies, pi. 

 54, figs. -70-72) were from this source. 



The typical form of aureus has close, waved stripes (figs. 70, 71), 

 but a plain form (fig. 72) occurs with it on the trees on Prince 

 Island. This unstriped color- variety is practically identical in char- 

 acters with leucoxanthus INIts. 



Dr. von Martens subsequently restricted the name aureus to 

 another snail, and referred Martyn's figures to melanomma, wrongly 

 identifying the locality with an island in the Straits of Malacca. 

 Afterward, von Martens referred Donovan's figures of some of the 

 Cook's voyage shells to leucoxanthus (Nachrbl., 1891, 34), still mis- 

 identifying the island where they were collected. 



The forms melanomma, natunensis arid leucoxanthus are apparently 

 varying geographic races of aureus. 



Var. MELANOMMA (Pfeiffer). PI. 55, figs. 80-86. 



Shell sinistral or dextral, imperforatc, oblong-ovate, solid and 

 strong; striatulate. Whitish (rose or cream tinted), with crowded 

 chestnut streaks, often irregular or ragged, and typically interrupted 

 by a yellow peripheral girdle, but this is frequently wanting. The 

 streaks may be either continuous from suture to base, or weak below 

 the suture, and leaving a white columellar patch. One or two 

 blackish varices generally present; upper whorls not streaked, white 

 or brown-banded ; apex deep purple, rarely white. Whorls 6^, the 

 last more or less concave below the suture. Aperture oblique, white 

 within ; peristome white, reflexed and recurved, but usually not adnate 

 behind, the edge white. Columella vertical, thick, its reflexed edge 

 generally covering the axial chink ; parietal callus strong and white, 

 deeply entering, often dark within. 



Length 46, diam. above aperture 21 mill. (Pfeiffer's type). 



Length 41, diarn. 24, longest axis of aperture 22 mill. 



Length 45, diam. 25, longest axis of aperture 25 mill. 



Length 52, diam. 28, longest axis of aperture 27 mill. 



Length 40, diam. 24^, longest axis of aperture 22 mill. 



Islands near Singapore, e$p. JRiouw or Rhio; and Biliton /., be- 

 tween Borneo and Banka, on bushes and low trees (A. Adams),, 

 11 



