140 



POST-TERTIARY ENTOMOSTRACA. 



an oblique direction, looking downwards and forwards ; posterior rounded and narrow, 

 terminating in a strong sharp spine; superior margin boldly arched, gibbous in the 

 middle, sloping steeply behind ; inferior almost straight. Seen from above, ovate, tumid. 

 Surface of the shell smooth, sparingly and minutely papillose : lucid spots about four in 

 number, large, and disposed obliquely, as is usual in the Cypridse. 

 Length, f^th of an inch. 

 One valve only of this species which appears, however, to be undoubtedly distinct, 

 occurred in the deposit met with on the site of the New Docks Basin at CardiflF. 



Famili/ 2.— DARWINBLLAD^. 



Genus — Darwinella, Brady and Robertson. 



PoLYCHELES, B. & R. Ann. and Mag. N. H., 1870, vol. vi, p. 25. 

 Darwinella, B. & R. lb., ser. iv, vol. ix, p. 50. 



Shell fragile, structureless. Carapace oblong, higher behind than in front ; lucid spots 

 ten to twelve in number, linear oblong or wedge-shaped, arranged in a subradiate manner 

 in front of the centre of the valve. Seen from the side, compressed, oblong, subovate ; 

 from above, ovate, acuminate in front, obtusely rounded behind. Valves unequal, the 

 right much larger than the left. Antennae very short and stout, strongly armed with 

 curved claws and bristles. Superior antennae six-jointed, having all the joints as broad as 

 or broader than long, and beset with stout curved setae ; inferior four-jointed, of nearly 

 equal thickness to the apex, which is armed with four or five strong, slightly curved claws, 

 entirely destitute of poison-gland or urticating setae, the place of which is occupied by a 

 simple curved seta of moderate length. Mandible broad ; truncate at the distal ex- 

 tremity which is provided with six or seven small and slender spiniform teeth ; palp 

 three-jointed, its basal joint very wide and fringed with a series of nine very long, curved 

 setae ; second joint long, slender, nearly four times as long as broad, slightly curved and 

 dilated at the distal extremity, where it bears one long and two small setae ; terminal joint 

 more slender, about two thirds of the length of the foregoing and bearing at the truncate 

 apex about six slender curved spines ; basal joint of the palp has attached to its 

 upper margin a small crescentic lamina which is fringed with ten branchial filaments. 

 Eirst jaw divided into four short setiferous segments, and bearing a very large oblong 

 palp which is fringed above with about twenty-four long branchial filaments, and has also 

 four deflexed setae at its base. Second jaw simple, short and wide, truncate at the apex 



