380 MOLLUSCA. 
Hipponizx imbricata, Goup; Proceed. Boston Soc. Nat. Hist., il. 
161. August 1846. Expedition Shells, 16. 
SHELL small, solid, of a slight fleshy tint, in the form of an ele- 
vated, slightly oblique cone. ‘The surface is rayed with forty to fifty 
sharp, elevated, regularly disposed, occasionally divaricating ribs, 
and these are crossed by the lamelle of growth, which are distant, 
regularly disposed, and as they pass over the ribs and intervening 
spaces, form beautifully vaulted tile-work. ‘The aperture is rounded- 
ovate, the margin expanded and fringed with the terminations of the 
ribs, and the interior is coloured deep crimson. Muscular cicatrices 
well impressed. 
Greatest diameter about two-fifths of an inch. Length, breadth, 
and height, in the proportion of 13, 11, 8. 
Inhabits the Sandwich Islands. 
Most like H. pilosa in sculpture, though the pattern is much 
coarser. The apex is far more central and elevated. The colour of 
the interior is like H. foliacea, Quoy, but more intense. 
Figures 490, 490a, 490, outer, inner, and profile views of the 
shell; 490, details of sculpture, enlarged. 
CaLYPTREA CHLORINA (Gould). 
Testa wrregularis, tenuis, concentrice undosa, liners elevatis acutis con- 
fertis radiata, ad basim subcircularis, oblique pyramidata, epidermide 
tenut chlorino induta ; apice elevato, postico, spiral, cernuo: intus 
nitida, porcellana; margine evoluto, acuto; lamina interiort semt- 
cyathiformt, brevi, reflexd, oblique truncata. 
Calyptrea chlorina, Gouin; Proceed. Boston Soc. Nat. Hist., 11. 
161. August 1846. Expedition Shells, 16. 
SHELL irregular, thin, waved concentrically, obliquely pyramidal, 
subcircular at base, marked with crowded, raised, acute, radiating 
lines, and covered with a thin, greenish-yellow epidermis; apex ele- 

