NUCULID&. 163 
trically ridged and decussated at both ends by radiating striz, these 
striz being absent from a small portion of the anterior central area ; 
anterior end short, rounded ; posterior longer; dorsal margin angled 
behind ; hinge slightly curved. 
Ieicht.-a5y; length, -7. 
Dead shells only have been found in New Zealand. 
Australia. Peru. 
Sub-Family—Pectunculine. 
Gills dependent ; foot securiform, simple, without any byssal groove 
at the base. Shell orbicular, with the hinge-margin semi-circular ; car- 
tilage in small marginal pits. 
Genus, PECTUNCULUS—Lamark. 
Orbicular, nearly equilateral, smooth or radiately striated ; umbones 
central, divided by a striated ligamental area; hinge semicircular ; 
adductors sub-equal ; pallial line simple ; margins crenated inside. 
P. laticostatus, Quoy, /.c., i1., p. 466, e¢ P. ovatus, Quoy, Le. iii., 
p. 467; P. laticostatus, Reeve, Conch. Lc., 7. 8. Orbicular, convex, thick, 
equilateral, with broad rounded radiating ribs, which become obsolete 
towards the margin in old individuals; finely concentrically striated ; 
six or eight teeth on each side, with a broad smooth area between them ; 
reddish-brown. interior white or brownish ; old shells are more or less 
truncated behind, and the young are often varied with white. 
Height, 3; length, 3. 
Auckland to Stewart Island. Chatham Islands. 
Found fossil in Australia, but not recent. The concentric strize 
soon wear off, and the shell often becomes quite smooth. 
P. flammeus, feeve, Conch. lc, f-7; P. grayanus, Dunker, P. 
Z.S., 1856, ~. 357. Shell rather triangular, white, vividly painted with 
reddish-brown, flaming triangular lines; teeth comparatively minute ; 
area of the ligament small (Reeve). 
Auckland. N.S. Wales. (Angas). . 
P. striatularis, Zamark, vi., p. 493; Heeve, Conch. Ic, f. 27, 
Chenu, f. 881. Orbicular, convex, thick, sub-equilateral, umbones curved 
slightly forwards ; finely radiately striate, and still more finely concen- 
trically striate ; teeth, seven to twelve on each side, not divided by a 
smooth space ; yellowish brown, more or less irregularly marked with 
reddish ; interior varied with brown. 
Height, 1; length, 1. 
Omaha. Stewart Island. 
FAMILY—NUCULID-%. 
Lips broad, triangular, large, striated internally, one in each pair of 
labial palps, long, curled, linear, and fimbriated at its margins, the other 
short and filiform. Mantle freely open, the edges simple, without 
