OF THE ANTWEEP CEAG. 383 



middle, and equal to somewhat less than one half the length. End view subcircular. 

 Surface of the shell perfectly smooth. Length -^ inch (0'75 millim.). 



A few specimens only in the " Sables moyens," zone a Bryozoaires. 



This species, when seen laterally, is very like P. trigonella, Sars, but is less attenuated, 

 and when seen from above is found to be much more tumid. 



Genus Bairdia, M'Coy. 



Valves unequal in size, the left much the larger and overlapping on the dorsal and 

 ventral surfaces. Shell nearly or quite smooth, mostly subrhomboidal or subtriangular. 

 Eyes wanting. Antennae robust; the upper 6-jointed, the first two joints being large 

 and thick, the rest short and bearing long setae. Lower antennae 5-jointed, the second 

 joint having on its base a bisetose tubercle. Mandibles large, having six or seven long, 

 strongly serrulated teeth ; palp 4-jointed, bearing a small trisetose branchial plate. 

 One pair of jaws only, 3-branched, and bearing a well-developed branchial appendage. 

 Three pairs of feet, all alike, directed forwards and protruding from the shell, 4-jointed, 

 and clawed at extremity ; first pair bearing at the base a large ovate branchial lamina. 

 Postabdominal rami short, clawed and setose. 



Bairdia oviformis, Speyer. (Plate LXIIL figs. 1 a-1 c.) 



Bairdia oviformis, Speyer, Die Ostracoden der Casseler Tertiarbildungen (1863), p. 44. pi. i. 

 fig. 6. 



Carapace, as seen from the side, broadly subtriangular, approaching to elliptical ; 

 greatest height situated in the middle and equal to two thirds of the length ; anterior 

 extremity broad, obliquely rounded ; posterior broad and slightly produced, so as to form 

 an almost obsolete beak ; dorsal margin strongly arched ; inferior slightly convex. Seen 

 from above, the outline is regularly ovate, pointed in front and broadly mucronate 

 behind, widest in the middle, the width being about equal to half the length. End view 

 broadly ovate, narrower above. The right valve considerably smaller than the left, 

 somewhat angular on the dorsal margin and distinctly beaked behind. Surface smooth. 

 Length -Yf inch (1'5 millim.). 



One specimen only of this fine species was found in the Isocardium-cor bed of the 

 " Sables moyens." 



Fam. CYTHERIDtE. 



Genus Ctthere, Miiller. 



Valves unequal, mostly oblong-ovate, subreniform or subquadrate ; surface smooth, 



punctate, rugose, spinous or tuberculated, usually bearing a rounded, polished tubercle 



over the anterior hinge-joint. Hinge formed on the right valve by two terminal teeth, 



on the left by one anterior tooth and a posterior fossa, between which there is often a 



