Late Cenozoic Ostracodes — Holden 
7 
Fig. 1. Cytherelloidea monodenticulata n. sp. a-b, Paratype sdnh 1025; a, side view of penultimate left 
valve; b, dorsal view showing toothlike structure, c, Paratype USNM 648713; side view of penultimate right 
valve, d-e, Holotype USNM 648712; d, side view of adult female left valve; e, dorsal view showing toothlike 
structure. 
mid-dorsum of left valve and equally well 
developed in penultimate instars; internal fea- 
tures not observed. 
dimensions: 
SPECIMEN 
LENGTH 
WIDTH 
HEIGHT 
Holotype usnm 648712 
(left valve, adult $ ) 
T-12 
0.67 
0.15 
0.35 
Paratype USNM 648713 
(right valve, young) 
T-12 
0.58 
0.10 
0.32 
Paratype sdnh 1025 
(left valve, young) 
T-12 
0.56 
0.10 
0.30 
Paratype usnm 648714 
(left valve, young) 
T-12 
0.52 
0.10 
0.30 
distribution: As fossils from T-12 (14 
valves). 
discussion: The prominent toothlike struc- 
ture in the mid-dorsum of the left valve is dis- 
tinctive; apparently it is a persistent feature 
occurring in both adult and penultimate instars. 
Cytherelloidea sp. of Keij (1953:156) from the 
Banda Sea, Netherlands East Indies, also shows 
a prominent tooth although it is not conspeciflc 
with C. monodenticulata n. sp. Van den Bold 
(1963) reviews this phenomenon in other spe- 
cies in the genus. 
The fairly smooth exterior, uncontorted by 
conspicuous depressions save for a subcentral 
depression, sets this species apart from the great 
majority of Indo-Pacific Cytherelloidea, such 
as those dealt with by Le Roy (1941), Brady 
(1880), Kingma (1948), and Keij (1964). 
The specific name refers to the single tooth- 
like structure near the mid-dorsum. 
Suborder podocopina Sars, 1866 
Superfamily bairdiacea Sars, 1888 
Family bairdidae Sars, 1888 
Genus Bairdia McCoy, 1844 
remarks: Sohn (1960:7, 12) points out that 
more than 600 species of Bairdia have been de- 
scribed from Ordovician to Recent ages, but 
that sexual dimorphism, at least of the hard 
parts, has gone unnoticed. Kornicker (1961) 
has shown, however, that certain living species 
of the genus from the Caribbean have taller 
males. Similar dimorphism apparently occurs 
in species of the present study. 
