Late Cenozoic Ostracodes — Holden 
11 
of B. foveolata of Brady (1880, figures 1 a-j) 
or the present species. 
Bairdia hanaumaensis n. sp. 
Figs. 5 a-h 
diagnosis: Finely pitted, centrally bulbous, 
ventrolaterally inflated carapace with ventral 
caudal process; elongate-oval in dorsal view. 
description: Carapace elongate, length 
about twice the height. In lateral view: greatest 
height anterodorsally; dorsoanterior straight, 
sloping at about 20° ; dorsoposterior straight, 
sloping at about 50°, ventroposterior and 
ventral margin continuous, straight ; ventro- 
anterior subtruncate, slightly convex. In anterior 
view: carapace flattened in dorsal half, highly 
inflated in ventral half. In dorsal view: sides 
only slightly convex, subparallel; anterior and 
posterior blunt; surface appears smooth but 
under high magnification is densely pitted ; 
living individuals evenly covered with short 
hairs and are uniformly brown in color. 
Adductor muscle scar pattern somewhat 
variable, usually of nine scars of various sizes 
and shapes ; two antennal scars anterior to 
lower adductor scars, posterior scar much 
smaller than other scars; copious mandibular 
scars just below adductor pattern ; several small 
mandibular scars throughout dorsal half of 
carapace. Anterior vestibule small ; posterior 
elongate, deepest posteriorly; radial pore canals 
straight, some bifurcating, with tendency to be 
paired; hinge typical of genus. 
dimensions: See Table 4. 
distribution: As fossils from T-12 (11 
valves) and AR (1 valve; 2 entire). Found 
living at 5 fathoms at HA (15 entire). 
discussion: The low, elongate carapace of 
Bairdia hanaumaensis is distinct from the ma- 
jority of bairdiids. However, B. acanthi ger a of 
Brady, 1880 and B. tuherculata Brady, 1880 
also have this general shape, the former being 
more comparable to B. hanaumaensis than the 
latter. B. acanthi gera of Brady, 1880, from 
1,070-1,150 fathoms in the North Atlantic, 
has a more rounded dorsum and ventral margin 
Fig. 5. Bairdia hanaumaensis n. sp. a, Paratype sdnh 1033; lateral view of right valve, b, Paratype usnm 
648727 ; internal view of left valve, c-e, Holotype usnm 648724; c, lateral view of entire carapace; d, dorsal 
view; e, anterior view, f, Paratype USNM 648725; internal view of right valve; antennal and mandibular scars 
in black, g, Paratype sdnh 1032; muscle scar pattern from left valve, h, Paratype usnm 648726; muscle scar 
pattern from left valve. 
