KNOWN SPECIES OF MARINE OSTRACODA. 365 
This appears to be a very distinct species, characterized chiefly by the brown hirsute 
carapace, rounded form of the valves, and the compressed oval outline as seen from 
above or below. I havea single valve from Honduras which is probably referable to 
the same species, but is rather intermediate in form between it and B. amygdaloides. 
5. Barrpia suBDELTOIDEA, Von Miinster. (Pl. LVII. fig. 8, a-h.) 
Cythere subdeltoidea, Von Minster, 1830, Jahrbuch fiir Mineralogie, p. 64. 
Bairdia subdeltoidea, Jones, 1849, Entom. of Cretaceous Formation, &c., p. 23, pl. 5. fig. 15, a-f. 
Bosquet, 1852, Entom. Fossiles des Terrains Tertiaires de la France, p. 29, pl. 1. fig. 13, a-d. 
Jones, 1856, Entom. of Tertiary Formation, p. 52, pl. 4. figs. 2a, 26,3; pl. 6. figs. 1 a, 1 4, 2. 
Egger, 1858, Ostrakoden der Miocin-Schichten, p. 5, t. 1. fig. 1, a-c. Speyer, 1863, Ostra- 
coden der Casseler-Tertiairbildungen, p. 43, t. 1. fig. 5, a-c (right valve), and B. oviformis, ib. 
fig. 6, a—c (left valve). 
Carapace triangular or subtriangular, convex. The Jeft valve is larger and much less 
angular than the right ; its ventral margin arched (sometimes flattened) ; dorsal margin 
inverted so as to overlap the opposite valve, broad and obliquely rounded in front, 
more or less produced, tapering, or beaked behind. The right valve is narrower, its 
dorsal border truncate in the middle; the ventral border sinuated and having a well- 
marked convex protuberance on the anterior third, strongly beaked posteriorly, broad 
and obliquely convex anteriorly: both extremities are often produced, in old specimens, 
into flattened, denticulate lamellz ; the dorsal edge is slightly inverted at its anterior 
and posterior thirds. Dorsal aspect oval or subrhomboid. nd view broadly ovate or 
suborbicular. Lucid spots arranged in a rosette, but seldom so regular as in the pre- 
ceding species. Surface of the valves smooth, often finely punctate, milk-white or 
pellucid with cloudy patches. The older specimens are mostly quite opaque. 
Length 35-a5 in. (1°27—846 mm.). 
Hab. Australia, West Indies, Turk’s Island, Crete (360 fathoms, Capt. Spratt), 
Serpho (Capt. Spratt). 
This species is very widely distributed both in the fossil and recent state; and there 
are a large number of varieties which appear to be fairly referable to it, being counected 
by a perfect gradation of intermediate forms. The surface-markings are very much 
dependent upon age, young specimens being generally pellucid, smooth, and free from 
hairiness or pittings ; adults milk-white in colour, often punctate or slightly pubescent ; 
while old specimens are more rugged in aspect, their punctuation obsolete, and the 
extremities occasionally developed into dentated lamin. Besides these various condi- 
tions, there are doubtless many varieties resulting from habitat, &c. I do not feel sure 
that the form described by the Rev. A. M. Norman! as Cythere (Bairdia) inflata is 
properly separable from B. subdeltoidea, though its much narrower form renders it, at 
least, a very distinct variety. Some examples of this form (B. inflata), dredged by 
1 Annals and Magazine of Natural History, 3rd series, vol. ix. plate 3. figs. 6, 7, 8. 
