LAND AND FRESH-WATER SHELLS. 349 



undei" exaininati(>ii, tlie gradual transition from one form to anntlier 

 is observable. 



(IG) Ifelix (Videna) s(inct(Z amies. (Plate XXXVL tigs. 7. 7 h.) Shell 

 depressed-conoid, deeply nmbilicated, very acutely keeled at the 

 periphery, light brown, sometimes with a few radiating pale streaks 

 on the npper surface, scnlptured with oblique lines of growth. 

 Whorls 5, rather slowly increasing, slightly convex, depressed and 

 margined above the suture, last not descending, compressed al)ove 

 and below the keel, a little convex towards the umbilicus, which is 

 moderately lai-ge. Aperture transverse, flesh-tinted within. Peris- 

 tome simple, a little thickened along the basal margin, with the ex- 

 tremities united liy a thin callus. Height 7 millim.; greatest 

 diameter 17, smallest 15. 



(25) C jidostoma {Adelostoma) triste, Tapparone Cauefri, var. 1 Dr. 

 Tapparone CanefVi has kindly compared specimens from these 

 islands with his C triste, and is of opinion that they may be con- 

 sidered a variety of it ; and observes that the New-Guinean foini 

 is a little smaller, its spire a little more slender, its surf.ice mure 

 glossy, the colour redder, and the apex of the spire darker. 



The shells under examination are clothed with a ver}^ thin 

 epidermis when in a fresh condition, exhibiting numerous very fine 

 spiral thread-like lines, which entirely disappear in worn shells and 

 can easily be rubbed off with a brush. For several species having a 

 similar epidermis and an incomplete peristome, Dr. Tapparone Canfri 

 has proposed the subgenus Adelostoma. 



(29) Ptipina solomonensis. (Plate XXXVL fig. 9, 9 a.) Shell small and 

 very like P. difficilis, Semper, and P. keraiidreni, Vignard. It is 

 of a reddish tint, especially the body-whorl ; consists of 5^ whorls, 

 which are the least convex and exhibit a pellucid line, frequently 

 brown, immediately beneath the suture. Last whorl very obliquely 

 descending behind, narrowed below, and flattened somewhat above 

 the aperture. Columella thickened with callus, white, parted oft 

 from the whorl above by an oblique circumscribing red line, trun 

 cated rather low down. Outer lip slightly thickened and effuse, 

 and a little paler than the rest of the whorl, produced somewhat at 

 its junction with the body-whorl, which in consequence has the 

 ayipearance of rising suddenly after an oblique descent. Length 7 

 millims., diam. 3f, aperture 2 long and wide. 



(34) Helicina solomonensis. (Plate XXXVL figs. 11, 11 h.) Shell small, 

 globose-conical, reddish or yellowish, pale at the apex. Whorls 4^ — 

 4|^, the least convex above, sculptured with lines of growth and fine 

 spiral stria) both on the upper and lower surfaces, very faintly 

 margined above at the suture ; last whorl rounded at the periphery, 

 obsoletely angled near the junction of the outer lip and the least 

 descending in front, so that the faint angulation is visible for a short 

 distance above the sutural line. Aperture somewhat semicircular 

 and oblique, small : peristome slightly expanded ; umbilical callosity 

 yellowish or pellucid whitish, defined towards the base of the 

 columellar margin. Greatest width 4|- millim., smallest 4 ; height 

 31. 



(44) Melania suhgradata. (Plate XXXVIL fig. 3, 3 a). Shell elongate, 

 turreted, rather solid, covered with an (olive?) epidermis, and 

 marked with fine longitudinal oblique red lines which extend from 

 suture to suture. Whorls probably about 10, flat or even a little 



