364 MOLLUSCA. 
bercles. Interior, shining, of a reddish chestnut or liver brown colour, 
pale and slightly crenulated at the edge. Muscular impression faint. 
Length three-fifths of an inch; breadth two-fifths; height one-fifth 
of an inch. 
Obtained at Burnt Island, Orange Harbour. 
Were it not for constant differences in the animal and shell, this 
might be regarded as the young of the very variable S. Lessont. But 
the apex, upon examination, never appears to have been so oblique at 
any stage of growth, nor so much prolonged or acute ; nor the surface 
so roughly ribbed. Its shape is very odd, and it looks as if the left side 
had been half cut away. 
Figure 462, the back of the shell; 462, 462, lateral and inferior 
views of the animal, with the shell. 
FIssURELLA OCCIDENS ( (Gould). 
Testa ovata, conica, valde elevata, radiatim multistriata, fasciis atro- 
purpureis ad quindecim et fascits rosaceis alternantibus radiata, 
apice subcentrali: apertura ovata: facies interna nivea, margine la- 
tiusculo, viridulo vel fusco tessellato: fissura rotundato-ovalis. 
Fissurella occidens, Goutp; Proceed. Boston Soc. Nat. Hist., 11. 156. 
August 1846. Expedition Shells, 13. 
Sue.i very elevated, conical, apex nearly central. Surface with 
fine radiating strie, and coloured with alternate rays of dark purple 
and light rose-colour, about fifteen of each. Aperture ovate. Interior 
pure dead-white, the margin dark greenish or livid, or with dusky 
spots answering to the dark rays. Fissure short, rounded oval. 
Length one inch and three-tenths; breadth one inch and one-tenth ; 
height eleven-twentieths of an inch. 
Inhabits Callao, Peru. 
