GASTEROPODA. 159 
semi-oval, the outer lip edged with indigo-blue, and bright pea-green 
within ; the inner lip is convex, pale yellowish-green; the columellar 
edge deeply sinuated and minutely denticulated. The operculum 
pale salmon-coloured, thick and bony, having a strong rib, which is 
most prominent inside, bisecting it; convex edge brown; columellar 
edge gibbous. 
Axis three-fourths of an inch; diameter three-fifths of an inch. 
Inhabits Upolu, Samoa Islands. 
Of the same group as N. communis, lugubris, and Turtoni, but dis- 
tinct by its green, blue-edged outer lip, and yellowish-green pillar lip, 
as well as by its very delicate zigzag lines, scarcely seen except on 
the ventral face. 
Figures 188, 188 a, two views of the shell. 
NERITINA AM@NA ( Croudd ). 
Testa parva, ovato-triangularis, posticé constricta, strits incrementalibus 
ordinatis bené insculpta, coloribus nigris, rubris, flavidis plerumque 
Sasciatim dispositis, et maculis quadratis albis nigro-umbratis tessel- 
latim dispositis, picta: spira planulata, erosa, anfractibus duobus vel 
tribus: apertura rotundato-elliptica, flavo-viridis; labro angusto, 
plano ; columella valde arcuata, decem denticulata. Operculum virt- 
dulum, inornatum. 
Neritina amena, Goutp ; Proceed. Boston Soc. Nat. Hist., ii. 238. 
July 1847. Expedition Shells, 49. 
SHELL small, of a triangular-ovate, gibbous form, shining, deli- 
cately marked with large, regularly disposed lines of growth, beauti- 
fully ornamented with various colours; generally, the ground is of a 
more or less rose-red tint, often alternating with black bands, more or 
less distinct, and the whole is thickly spotted with small quadrangular 
white spots, which cast long, conical, black shadows toward the aper- 
ture. Spire not elevated, but even a little depressed, eroded, of two 
or three whorls; suture distinct. Aperture rather long, rounded-ovate, 
