526 Mr. II. B. Preston on new 



liOYBELLlA, gen. nov. (Zonitidce). 



Shell very depressed, thin, horny, yellowish brown, trans- 

 versely costulate, strongly and acutely carinate at the peri- 

 phery, the termination of the costulae projecting beyond the 

 margin of the carina. 



Genotype: Trochonanina plalysoma, Sykes *. 



Roybellia depressa, sp. n. 



Shell differing from Trochonanina platysoma, Sykes, in 

 its much more depressed form, the spire having a laterally 

 concave appearance, the transverse costulae are finer than in 

 1\ platysoma, and the surface of the shell is microscopically 

 granulate, while the peripheral carina is produced into a pro- 

 jecting flange ; the base is also less inflated, thus almost 

 entirely eliminating the umbilical depression which is seen in 

 Sykes's species. 



Alt. 1*5, diam. maj. &'5 (nearly), diam. min. 5'5 mm. 



Aperture: alt. 1*5, diam. 3 mm. 



Bab. Mount Pitt, Norfolk Island (R. Bell). 



Fretum microstriatum, sp. n. 



Shell depressedly turbinate, without trace of colour; 

 whorls 41, the last ascending a little in front, regularly and 

 rather rapidly increasing, sculptured with very fine, wavy, 

 closely set, microscopic, spiral striae, and marked with fine, 

 indistinct, transverse growth-plicae; suture rather lightly 

 impressed ; base of shell moderately convex ; columella 

 margin callously thickened and inwardly bulging above, then 

 slightly excavatedly curved, and obliquely descending below; 

 labrum simple; aperture broadly and depressedly sublunate. 



Alt. 10, diam. maj. 16, diam. min. 14 mm. 



Aperture: alt. 8, diam. 8 mm. 



Hob. Norfolk Island, subfossil in sand near the limestone 

 quarry on the S.E. coast (R. Bell). 



Adcena campbellii (Gray), var. charon, var. n. 



Shell differing from the typical form in having the earlier 

 whorls of a dark crimson colour, below which the whole shell, 

 with the exception of the supersutural, extreme carinal 

 margins and the columella, is ot a uniform blacki.-h-brown 

 colour. 



Bab. Mount Pitt, Norfolk Island (R Bell). 



* Proc. Malac, Soc. London, vol. iv. 1900, p. ]40, pi. xiii. figs. 16, 17. 



