Late Cenozoic Ostracodes — Holden 
23 
Fig. 15. Hemicythere sp. a-c, Specimen usnm 648746; a, external side view of left valve; b, internal view; 
adductor scars in white; c, dorsal view. 
Hinge modified holamphidont: posterior ele- 
ment trilobed ; anterior element an entire tooth ; 
median bar smooth, with smooth, somewhat 
subdued anterior tooth, posterior part of bar 
projecting (in dorsal view). 
Adductor muscle scar pattern distinctive: 
curved, near-vertical row of four rounded scars 
on side of shallow depression; top, bottom, and 
one of middle scars divided into two distinct 
scars respectively ; two antennal scars on anterior 
side of depression; single (?) weak dorsal 
mandibular scar present. Radial pore canals 
moderately abundant, straight, few in anter- 
oventer with midswellings; normal pore canals 
numerous, causing deep internal depressions, 
pores not coinciding necessarily with external 
lows (some extend through the heavy orna- 
mentation). Moderate selvage present in left 
valve. 
dimensions: Specimen usnm 648746 (left 
valve) T-12: length, 0.65; height, 0.35; 
width, 0.20. 
distribution: As fossils from T-l (1 valve), 
T-ll (1 entire), and T-12 (1 valve). 
discussion : Hemicythere sp. is in many ways 
comparable to H. obesa. An inflated carapace 
with large internal pits, ventrally notched pos- 
terior hinge element, and general shape are 
common to both species. H. sp., however, is 
smaller, coarsely ornamented, and has a differ- 
ent muscle scar pattern than H. obesa. Here, 
as in the latter species, H. sp. disagrees with the 
generic concept by having an almost hemi- 
amphidont hinge and an atypically divided ad- 
ductor muscle scar pattern. 
Genus Mutilus Neviani, 1928 
Mutilus ( Mutilus ) oahuensis n. sp. 
Figs. 16 a-b 
diagnosis: Conspicuous left valve overreach; 
combined ornamentation of large reticulations; 
pronounced bladelike marginal and lateral 
ridges. 
