176 AMPHIDROMUS, GROUP VI. 



Alt. 01, diam. 47.5 mill. 



Annam: "Mother awl child" mountain (Roebelen). 



A. in ye us MLLDFK., Nachrbl. xxxii, p. 23 (Feb., 1900). 



" This very remarkable form exceeds the largest species known to 

 this time, A. c'tmbnjiensis Rve. in size, and is very notable for the 

 singular girdling with three strongly raised welts, and the deep fur- 

 row below the middle welt. This structure is lost upon the penulti- 

 mate whorl, and is represented on the earlier whorls only liy a grad- 

 ually weakening impression along the suture. The rather prolonged 

 base of the mouth somewhat recalls A. inauris Bttg. of Java. Noth- 

 ing certain can be said of the color, but it appears to lie pure \\hite. 

 The specimens, though obviously collected alive, are partly covered 

 with algse, and show no trace of a colored cuticle." (Mlldjf.) 



A. COSTIFEK Smith. PL 59, figs. 22, 23. 



Shell rimate, ovate, dextral, solid; whitish, the last whorl more 

 or less streaked and variegated with* purple-brown above. Whorls 

 T>, a little convex, separated by a slightly oblique suture, striated with 

 growth-lines (rugose on the last whorl), cut by obsolete spiral stria-, 

 the hist whorl having a very oblique, strong trltite varix on the back. 

 Aperture widely subaiiriform, half the total length of the shell, 

 whitish within ; peristome white, thickened, the right margin 

 slightly reflexed, columellar margin widely dilated, joined to the lip 

 by a very broad, thick, white callus; columella subperpendicular, 

 slightly twisted. Spire conoid, with convex outlines. Length 47, 

 diam. 24, aperture inside L' 1 mill. long. (Smith.) 



Annam: *' duns Ics montagnes bailees du Huyen de Triphuoc, pro- 

 vince Binh - dinh " ( E . E u d e 1 ) . 



Amphidromus costifn' E. A. SMITH, Proc. Malac. Soc. Lond., i, 

 p. 12, figs, in text (1898). FCI,TOX, Ann. Mag. N. H. (('), xvii, p. 

 91, pi. 7, f. <J, 6 (189C,). 



This species is remarkable for its short, ovate form, the some- 

 what rugose lines of growth, Jind its irregular auriform aperture ; but 

 especially for the varix or former lip on the back of the body-whorl. 

 This apparently indicates a period of arrested growth, probably of 

 ilie previous year. It occurs in all the specimens as yet known, 

 seven in number, with the exception of one of immature growth. 

 This is in nice fresh condition, and shows that the color of the species 

 is much brighter in the young shells. Beneath the suture the whorls 



