58 MOLLUSCA. 
Diameter seven-tenths of an inch; axis one-fourth of an inch. 
Inhabits the Society and Samoa Islands. Couthouy. 
In many respects this is similar to H. Tyozlus, but it is more lenti- 
cular, and the whorls are less rounded. It is flatter beneath, and the 
colours are very differently disposed. The surface, though shining, 
is everywhere striated vertically, with sharp lines. In shape it is 
much like H. acies, Fer., but it is smaller and flatter underneath. 
Figure 56, shell from above; 56a, 566, 56c¢, three views of the 
green variety, 
Hexix Trois (Gould). 
Testa variabilis, depresso-conica, sub-discoidea, leviter et obtusé striata, 
SJlavescens, subtus convexa, in umbilicum amplum incurvata, carinata ; 
carina utroque linea spirali castanea marginata: interdum coloribus 
inversis: spira anfractibus quinque cum dimidio, rotundatis : apertura 
semilunars, superne angulata ; labro acuto. 
Hehz (Carocolla) Trewlus, Goutp ; Proceed. Boston Soc. Nat. Hist., 
il. 176. Sept. 1846. Expedition Shells, 23. Premrer ; Monog., i. 123. 
Animat pale, pearly-violaceous anteriorly, yellowish-green poste- 
riorly ; a dark line runs backward from each tentacle; no distinct 
lateral furrow. 
SHELL very variable, of a depressed, orbicular form, with sharp and 
conspicuous lines of growth, widely and deeply umbilicated, more or 
less sharply angular at periphery, colour reddish-brown, honey-yellow, 
or pale green, disposed in bands of greater or less width. _Whorls five 
or six, moderately convex. Aperture transverse, lip simple, slightly 
expanding as it approaches the umbilicus; throat tinged with pale 
violet. 
The principal varieties are as follows :— 
a. SHELL depressed, rounded, thick, of a deep brown colour, paler 
