24 
PACIFIC SCIENCE, Vol. XXI, January 1967 
Fig. 16. Mutilus ( Mutilus ) oahuensis n. sp. a-b, Holotype usnm 648751; a, right valve view of entire 
carapace showing dorsally overreaching left valve; b, dorsal view. Mutilus ( Mutilus ) palosensis (Le Roy), 
1943- c, Plesiotype usnm 648748; internal view of right valve; adductor scars in white, d-e, Plesiotype usnm 
648747 ; d, right valve view of entire carapace showing slight overreach of left valve; e, dorsal view. 
description: In lateral view: anterior mar- 
gin blunt, somewhat flattened in dorsal part, 
more tightly rounded in ventral part; ventral 
margin slightly concave; dorsal margin gently 
convex in both valves; posterior margin concave 
above distinct low caudal process. Left valve 
considerably overreaching but not strongly over- 
lapping right valve dorsally ; ornamentation 
distinctive ; surface covered by large deep reticu- 
lations bordered by high massive bladelike 
ridges ; marginal ridges same ; dorsal ridge turn- 
ing abruptly anteroventrally at posterodorsal 
angle, forming high oblique lateral ridge; ven- 
trolateral ridge also prominent. Eye tubercle 
below anterodorsal angle indistinct, located at 
juncture of dorsal and anterior marginal ridges 
and sinuous vertical ridge. Internal features not 
observed. 
DIMENSIONS: 
SPECIMEN 
LENGTH 
WIDTH 
HEIGHT 
Holotype usnm 648751 
(entire) AR 
0.75 
0.39 
0.47 
Paratype usnm 648752 
(entire) AR 
0.72 
0.43 
0.46 
Paratype usnm 648753 
(entire) AR 
0.75 
0.36 
0.45 
Paratype SDNH 1043 
(entire) AR 
0.70 
0.35 
0.41 
Paratype sdnh 1044 
(entire) AR 
0.74 
0.37 
0.46 
distribution: As fossils from AR (1 
valve; 
7 entire) . 
discussion: The internal features of this 
species are not preserved; however, a Recent 
species, Mutilus palosensis (LeRoy), 1943, 
from Alijos Rocks, Mexico, most certainly a 
