GASTEROPODA. 165 
ANIMAL violaceous, foot beneath margined by a series of small, 
alternately dark and light spots; mantle bluish-black, mottled with 
short black lines. Head very short, regularly curved in front, mar- 
gined by a dark line; body above of the same colour, marbled with 
white and tessellated at the margin. Tentacles very long, annulated ; 
eye pedicles small, distinct. Opercle rusty-brown. 
Inhabits Tahiti, Society Islands. 
Figure 191, shell, with the animal as in motion. 
NERITINA HELVOLA (GouLD); Proceed. Boston Soc. Nat. Hist., ii. 
238, proves to be Nerzta Turtont, Recluz; Proc. Zool. Soc., 1843, p. 71. 
It inhabits the Feejee Islands, and seems to be abundant. 
NERITA Musiva (Gould). 
Testa modica, subsolida, transversa, ovoidea, ventricosa, fusco-cinerea, 
longitudinaliter crassé striata, sulcis volventibus ordinatis arata, liris 
interpositis planulatis, sub-granulosis, lineolis crebris albidis sectis : 
spira prominula ; anfractibus duobus vel tribus: apertura sub-circu- 
laris, caliciformis ; peristomate sub-continuo ; labro edentulo, albo, sulcis 
obliquis fuscis tenuiter arato,; labio concavo, fusco, granulis paucis 
notato, denticulis tribus instructo. 
Nerita musiva, Goutp; Proceed. Boston Soc. Nat. Hist., ii. 238. 
July 1847. Expedition Shells, 49. 
SHELL small, rather solid, very oblique, almost transversely ovate, 
its dorsal face much elevated and rounded, of a generally gray colour, 
produced by a dirty black ground, tessellated by ash-coloured, minute, 
crowded lines, which cross the ribs, as well as by coarse lines of 
growth, giving a fine mosaic appearance; it has an ash-coloured band, 
occupying two ribs around the last whorl, and sometimes also undu- 
lating mottlings. Surface ploughed with spiral grooves, so as to form 
numerous flattened ribs. Spire two to three whorls, rather prominent, 
sub-cylindrical. Aperture large, lateral; nearly circular, the peri- 
treme nearly continuous; callus citron; right edge tessellated ; within 
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