Late Cenozoic Ostracodes — Holden 
15 
Bairdia expansa Brady, 1880 
Figs. 8 a-d 
Bairdia expansa Brady, 1880, Rept. Voyage 
Challenger, Zool. 1, pt. 3, p. 58, pi. 11, figs. 
2 a—e. 
diagnosis: Small, greatly inflated carapace, 
compressed in antero-posterolateral regions ; 
high anterocardinal angle ; abrupt upturned 
posteroventer ; smooth porcelaneous surface. 
description: In lateral view: carapace 
greatly inflated midventrolaterally ; dorsopos- 
terior concave in posterior part, continuous with 
broadly rounded dorsal margin; dorsoanterior 
concave; ventroanterior bluntly rounded, with 
few scattered denticles ; ventral margin straight, 
convex with ventrally extended inflation; ven- 
troposterior abruptly rounded with several den- 
ticulations; surface of carapace smooth, appar- 
ently imperforate, with porcelaneous texture. 
In dorsal view: greatest width medially; later- 
ally compressed at ends giving concave lateral 
extremities; left valve strongly overlapping 
right valve. 
Duplicature moderately wide. Adductor mus- 
cle scar pattern apparently large, of many 
smaller scars. 
dimensions: 
PLESIOTYPE 
LENGTH 
WIDTH 
HEIGHT 
USNM 648739 
(adult left valve) 
T-12 
0.84 
0.34 
0.48± 
SDNH 1038 
(penultimate left valve) 
T-12 
0.70 
0.24 
0.40 
distribution: As fossils from T-12 (3 
Fig. 8. Bairdia expansa Brady, 1880. a-c, Plesiotype usnm 648739; a, internal view of broken left valve; 
b, lateral view showing dashed line reconstruction; c, dorsal view, d, Plesiotype sdnh 1038; lateral view of 
penultimate left valve. 
