38 
PACIFIC SCIENCE, Vol. XXI, January 1967 
Fig. 27. Paradoxostoma sp. B. a-b, Specimen usnm 648785; a, internal view of broken left valve; 
b, exterior view. 
Paradoxostoma cf. P. rubrum G. W. Muller, 
1894 
Figs. 28 a-c 
description: In lateral view: carapace nar- 
row; dorsum broadly arched; greatest height 
just behind midlength; venter slightly concave; 
anterior somewhat pointed ; posterior with nar- 
row caudal process; surface smooth; in dorsal 
view: posteriorly pointed, less pointed ante- 
riorly; greatest width midlength. Duplicature 
wide, especially in anterior. 
dimensions: Specimen usnm 648786 
(broken right valve) T-4: length, 0.58; width, 
0.07; height, 0.18. 
distribution: As fossil from T-4 (1 valve). 
Paradoxostoma rubrum Muller, 1894 occurs 
with calcareous algae in the bay of Naples. 
discussion: The extremely thin, low cara- 
pace with duplicature suggests that the species 
belongs in the family Paradoxostomatidae. 
Though placed in the genus Paradoxostoma, 
following Muller (1894), the present specimen, 
together with P. rubrum Muller, may warrant 
new generic status. 
The fossil specimen from Hawaii is com- 
parable, but not conspecific, with Paradoxo- 
stoma rubrum Muller, 1894 from the Gulf of 
Naples, Italy. These two forms are certainly 
closely related and differ only in details of shape. 
Genus Sclerochilus Sars, 1866 
Sclerochilus sp. A 
Figs. 29 a-b 
description: In lateral view: shell elongate, 
length 2-J times the height ; dorsum broadly and 
evenly rounded ; anterior abruptly rounded, 
subtruncate; an tero venter concave, postero- 
venter slightly convex; surface completely 
smooth. Internal features not preserved; hinge 
apparently adont. 
dimensions: Specimen usnm 648787 (left 
Fig. 28. Paradoxostoma cf. P. rubrum G. W. Muller, 1894. a-c, Specimen usnm 648786; a, side view 
of right valve; b, dorsal view; caudal process broken; c, internal view showing wide anterior duplicature. 
