Late Cenozoic Ostracodes — Holden 
25 
closely related form, has typical hemicytherid 
internal features. Specimens from Alijos Rocks 
are illustrated for comparative purposes (Figs. 
1 6 c—e). Though very similar in general shape 
and ornamentation, the Hawaiian fossil species 
is shorter, the larger left valve is relatively 
higher than the right valve, and the dorsum is 
straight. Also, the reticulations in the fossil 
form are deeper and the ridges more bladelike 
than in M. palosensis. 
Mutilus(P) coalescens n. sp. 
Figs. 17 a—d 
diagnosis : Ornamentated with coalescing 
heavy knobs and poorly defined ridges; highly 
inflated, subquadrate carapace. 
description: Carapace tumid, as wide as 
high or wider; left valve slightly larger, over- 
lapping right valve at terminal hinge elements 
and ventral inturned area. In lateral view: dor- 
sal margin straight to slightly convex; anterior 
and posterior margins subtruncate, anterior 
margin sloping down about 60° from the hori- 
zontal from sharp anterodorsal angle; posterior 
margin straight, sloping down about 75° from 
sharp posterodorsal angle to inconspicuous low 
caudal process ; ventral margin straight to 
slightly concave, terminating at caudal process. 
Fig. 17. Mutilus (?) coalescens n. sp. a-b, Holotype usnm 648762, right valve view of entire female (?) 
carapace; b, dorsal view, c, Paratype usnm 648763; internal view of female (?) right valve; abductor scars 
in white, d, Paratype sdnh 1045; internal view of male (?) left valve; adductor scars in white, e, Paratype 
usnm 648764; dorsal view of entire female (?) showing deep dorsal groove, f, Paratype sdnh 1046; right 
valve view of entire male (?) showing slight overlap of left valve. 
