448 MOLLUSCA. 
somewhat alate, compressed, the margin obliquely and somewhat con- 
cavely truncate, somewhat nasutely terminated: the anterior and 
basal margins forming a continuous curve. The ligament margin is 
delicate and narrow, furnished with about five notches. Interior 
somewhat silvery. 
Length an inch and a quarter; height five-eighths of an inch; 
breadth three-eighths of an inch. 
Inhabits the Feejee Islands. 
None of the species already described agree with this in colour, 
texture, or form. Its structure is very delicate and unresisting, almost 
fibrous at its edge. 
Figures 584, 584 a, lateral and dorsal views of the shell; 5844, the 
hinge. 
PINNA SENTICOSA (Gould). 
T. cuneata, subinflata, posticée oblique rotundata, purpureo-nigricans ; 
margine dorsali subascendente ; margine ventrali propé apicem pen- 
dulo: area superior triangularis costults ad septem radiantibus squa- 
migeris (squamis semi-tubulosis) instructa ; area inferior striis incre- 
mentalibus solum notata. 
Pinna senticosa, Goutp; Proceed. Boston Soc. Nat. Hist., iii. 312. 
Nov. 1850. Expedition Shells, 92. 
SHELL wedge-shaped, somewhat inflated, rather firm, of a dusky 
colour, inclined to purple, especially near the apex. ‘The dorsal mar- 
gin is slightly ascending, ventral margin suddenly pendent, about an 
inch from the apex; posterior margin slightly oblique, obtusely 
rounded. Above a line running from the apex to the inferior poste- 
rior angle, the surface is occupied by about seven small, diverging 
ribs, bearing rather distant vaulted scales, which become semi-tubular 
near the end, with also some raised lines in the intervening spaces ; 
the lower portion is plain, except that it is rather deeply marked by 
the lines of growth. 
