OF CONCHOLOGY. 219 



DESCRIPTIONS OF NEW SPECIES OP LAND AND FRESH- 

 WATER SHELLS. 



BY ANDREW J. GARRETT, 

 Of Tahiti, South Seas. 



Neritina holosericea, Garrett. Plate 19, fig. 1. 



Shell subglobose, transverse, rather thin, olive-gray under a 

 brownish velvety epidermis ; spire small, obtuse ; whorls three, 

 strongly convex, the last one large, subglobose, transverse, ra- 

 diately plicate above, spirally lineated with fine elevated, closely- 

 set, scabrous striae, which are about the same width as their in- 

 terspaces ; aperture semi-circular, diagonal, bluish within, and 

 the lips honey-yellow; peristome rounded, rather sharp, slightly 

 labiate within ; columella flattened, minutely granulated, the 

 margin slightly oblique, sinuous, with 10 — 12 teeth : operculum 

 pale corneous, stained with blue-black. 



Length, 10 mill. ; greatest diam., 12 mill. 



Habitat, Vanna Lavu, Viti Isles. 



Coll. Garrett and Philad. Academy. 



Nearly 100 examples of this species were found on a half- 

 decayed log on a mud flat on the north coast of Natawa Bay. 

 Not a single specimen was found in any other part of the group. 

 The spiral lines and velvety epidermis are its most obvious char- 

 acters. 



Plecotrema hirsuta, Grt. Plate 19, fig. 2. 



Shell imperforate, solid, corneous ; spire acute, convexly-coni- 

 cal, nearly half the length of the shell ; whorls 8 — 9 (two em- 

 bryonal), plano-convex, the last swollen, transversely sulcate, 

 sulci deep, nearly as wide as the intervening ridges, 16 — 18 on 

 the body, garnished with sl^ort curved hairs ; sutures obsoletely 



