THE CRETACEOUS EORMMTON. 
No. 2. Bairdia Siliqua, noUs. Tab. V, fisr. 16 a — h. 
Var. rt. 
Var. ( 3 . 
INCH. 
INCH. 
INCH. 
Length, 
1 
1 2 
1 
2 0 
1 
Height, 
1 
3 0 
1 
,5 0 
1 
(J 0 
Thickness, 
1 
4 0 
1 
5 0 
1 
U(7 
Var. a. Detritus, Charing. 
— Recent, Tenedos (hairy). ^ 
Detritus, Charing. 
Chalk, South-East England. 
Var. (3. Detritus, Charing. 
— Miocene, Bordeaux. 
— Recent, Turk’s Island, Bahama. 
Carapace elongate, sub-triangular. Valves narrow, convex, sometimes spined, 
generally smooth, acuminate behind. Dorsal margin strongly arched, slanting off 
posteriorly ; ventral nearly straight. Anterior extremitg rounded ; posterior acute. 
Dorsal edge of rigid (large) valve inverted near the middle ; ventral edge inverted nearly 
its whole length. 
Dorsal aspect narrow lanceolate ; anterior acutely ovate. 
Variety a (figs. 16 c, 16/, 16/, about two thirds the length and height of the fore- 
going, but comparatively more gibbous. Dorsal margin more prominent ; ventral 
incurved. 
Dorsal aspect elongated oval ; anterior oval. 
Variety f3 (fig. 16 h), about the length of Var. «, very narrow, strongly bent, 
incurved at the ventral, and arched at the dorsal border. 
Dorscd aspect narrow lanceolate ; anterior suborbicular. 
We have met with D. Siliqua only in the Chalk and the Detritus. Perfect valves 
and carapaces of this elegant and fragile species are not easily obtainable from the 
Chalk. In the Detritus, however, perfect and united valves often occur. A hirsute 
individual of Variety a occurs at Tenedos.^ Carapaces apparently identical with 
Var. j3 occur amongst the Fossil Entomostraca of Bordeaux, and recent in Turk’s 
Island, Bahama. We may remark that D. Siliqua bears a striking resemblance to 
Cyris fasciatn, AI filler (Entomostraca, p. 53, n. 12, pi. iv, figs. 1-3), and to Oggoris 
ephipptiata, Koch (1837, Deutschl. Crustac., Heft 12, t. 1). 
No. 3. Bairdia Harrisiana, nohis. 
INCH, INCH. 
Length, dt iv ^ 
Height, 
Thickness, dz 
Tab. VI, fig. 17 a—f 
Speeton Clay, Yorkshire. 
Gault, Leacon Hill. 
Detritus, Charing. 
Chalk, Gravesend and Charlton. 
Carboniferous Limestoire, East Kilbride. Recent, Mouth of Thames. 
— Manilla (hairy). ^ 
Carapace elongate, arcuated, varying in the flexuosity of the ventral border. 
1 In Mr. Williamson’s Collection. ^ Specimens of this size are very rare. 
E 
