GASTEROPODA.. 33 



FAMILY NERITID.E. 



Shell thick, semi-globose ; spire very small ; cavity simple ; aperture 

 semi-lunate; columella expanded and flattened; outer lip acute; oper- 

 culum shelly, sub-spiral, articulated. 



NERITA. 



Shell smooth or spirally grooved; epidermis horny; outer lip 

 thickened and sometimes denticulated within ; columella with its inner 

 edge straight and toothed. 



Warm seas. 



138. N. atrata, Lamark, I.e., viii., p. 603 ; IF. nigra, Gray, Dieff". 

 N.Z., ii ,p. 24:0. Shell spirally striate ; blue black ; white and chalky 

 when eroded ; interior grey, columella and near the mouth white, 

 mouth and outer edge of columella blue black ; operculum papillose 

 outside, pale purple, with two spiral bands of blackish purple. Length, 

 7 ; breadth, 1. 



Common. 



FAMILY TnocnnxE. 



Shell spiral, turbinated or pyramidal, pearly inside ; operculum 

 calcareous and pauci-spiral, or horny and multi-spiral. 



TURBO. 



Turbiuated, solid, whorls convex ; aperture large, rounded, slightly 

 produced in front ; operculum shelly and solid, callous outside, in- 

 ternally horny and pauci-spiral. 



Tropical seas. 



139. T. smaragdllS, Lamark, I.e., ix., p. 191. Sub-globose, im- 

 perforate; smooth, or slightly roughened with oblique transverse striaD ; 

 columella flattened. Blackish green, covered with a brown epidermis 

 (old worn dead shells are sometimes pink) ; inside white, slightly 

 iridescent; mouth dark green. Length, 2'25 ; breadth, 2 '4 ; angle of 

 spire, 85 to 103. 



Var. B. Spire whorls with one. and body whorl with three, spiral 

 rounded ribs ; columella generally dilated and flattened anteriorly. 

 In the young the spire whorls are sometimes sub-spinose. 

 Common. 



140. T. (Modelia) rubiciindus, Reeve, Proc. Zooi. 



1842. Sub-globose, imperforate, with spiral moniliforrn ribs, whorls 

 four ; columella with a sinistral depression. Reddish purple, varied 

 with white ; interior white, slightly iridescent. Length, 2'15 ; breadth, 

 2 35 ; angle of spire, 85. 

 Chatham Islands. 



141. T. (Modelia) granOSUS, Lamark, I.e., ix., p. 137. Tur- 

 binate, imperforate ; whorls five or six, rather convex, with spiral 



moniliform lines. Eeddish ochraceous, the spiral lines alternately 



