GASTEROPODA. 101 
lines of increment, of a lemon colour, or banded with reddish-brown, 
or entirely reddish-brown. Whorls four, slightly convex, separated 
by a well-marked suture, the outer one rounded at the periphery, but 
rather compressed. Beneath nearly as convex as above. Aperture 
rather broadly lunate; lip sharp and simple, angulated as it rises on 
the left, where it is broadly expanded into a rather copious callus. 
Length of axis one-tenth of an inch; breadth three-twentieths of 
an inch. 
Inhabits Tahiti and Eimeo. Couthouy. 
Figures 110, 110a, 110 4, three views of the shell, enlarged; 110 c, 
natural size, with the animal. 
One of the smallest known species. It is like a small Singapore 
species, which has a smooth, depressed spire, solid shell, and rib-like 
carina about the periphery, and an expanding lip. It is principally 
remarkable for its variable colouring. 
CyciostToma TIARA (Gould). 
Testa solida, rudis, turbinata, distorta, sordidé alba, laté umbilicata : 
spira anfractibus quinque laxis, rotundatis, spiraliter liratis, supernis 
undulatis ; inter liros lineis incrementalibus conferté clathratis : aper- 
tura circularts ; pertstomate simplice. 
Cyclostoma tiara, GouLD ; Proceed. Boston Soc. Nat. Hist., ii. 204. 
March 1847. Expedition Shells, 37. 
Suet solid, turban-shaped, or depressed-conical, of a dirty, ashy 
white, the surface rude, usually having coarse and unequal revolving 
lines, and with the smaller whorls feebly undulated ; the spaces between 
the revolving lines are closely barred by the lines of growth. There 
are six whorls, which are more or less carinated at the periphery, 
the last of which is somewhat distorted, and becomes nearly disjoined 
from the preceding near the aperture. The whorls are rounded 
below, and form a large and deep umbilicus, displaying all the whorls. 
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