Molluscan Assemblages — Okutani 
89 
shape; quadrangular in outline; beak anteriorly 
oblique; surface rough, uniformly pink in color, 
sometimes with delicate wavy pattern of darker 
color on posterior region; radial ribs running 
from umbo to distal margin, 20 or 21 in num- 
ber, as wide as shallow interspacial grooves, 
granulated on anteroventral ones, while sparsely 
spinose on rest; longest spinose scale as long as 
V 5 of shell length; escutcheon narrow; lunule 
deeply impressed, cordate in outline. 
Interior smooth, with shallow radial grooves; 
ashy white with pinkish tint; on right valve, 
anterior cardinal teeth vestigial, while posterior 
ones elongated; on left valve, anterior cardinal 
teeth short, small but prominent, posterior ones 
elongated, plate-like in shape; ventral margin 
crenulated; mantle scar smooth. 
locality: 35° 50' N, 130° 28.5' E, 210 m in 
depth, gravels and shell. 
TYPES: Left odd valve: 16 mm long, 13 mm 
high, 5.5 mm thick (holotype). Left odd valve: 
13 mm long, 11.5 mm high, 5 mm thick (para- 
type). Right odd valve: 18 mm long, 16 mm 
high, 7 mm thick (paratype). 
REMARKS: This new species is closely allied 
to G. hirasei (Dali), 2 but the latter has more 
radial ribs which are closely scaly. This new 
species is distinguished from G. millegranosa 
(Nomura and Zimbo), 3 which has a strongly 
inflated shell and granulated radial ribs. 
DISTRIBUTION: The type locality and off Kii 
Peninsula (collected by Mr. Teramachi; con- 
joined valve measures 24 X 20 X 18 mm). 
2 Dali, 1918: Proc. U. S. Nat. Mus. 54(2234) : 234. 
3 Nomura and Zimbo, 1934: Sci. Rept. Tohoku 
Imp. Univ., 2nd ser., 16(2): 154(45), pi. v(i), 
figs. 13a, b, 14a, b. Also Okutani, 1958: Venus 20: 
220, tfs. 2, 3. 
