390 DR. G. S. BRADY ON THE OSTRACODA 



surface of the valves usually more or less beset with small circiilar pits (but sometimes 

 quite smooth), and having a large central rounded tubercle ; anterior and posterior 

 margins produced into wide, thickened, and rounded lips, and fringed with numerous 

 fine teeth, usually a large number in front, but only five or six behind. Length ^ inch 

 (0-75 millim.). 



This is perhaps the most abundant of all the species found in the Antwerp Crag, 

 occurring in great plenty in the Panopma and Pectunculus-heds, not quite so commonly 

 in the sables a Biyozoaires, and is quite scarce in the Trophon- and Isocardhrm-heds. It 

 is remarkable that the species has not been found in the English Tertiaries ; and one 

 specimen only is on record from the Post-tertiary deposit of Hopton Cliff, near Yarmouth 

 It occurs in a living condition in the northern portions of the North Sea (Norway and 

 Shetland), also in the Gulf of St. Lawrence (Canada). 



Cytheee wetheeellii, Jones. (Plate LXIV. figs. la-Id.) 



Cythere wetherellii, Jones, Quart. Journ. Geol. Soc. x. p. 161, pi. iii. fig. 9 ; Tertiary Entomost. 

 England, p. 26, pi. iv. fig. 15, and pi. vi. figs. 16a-16c?. 



Carapace, as seen from the side, subquadrate, much higher in front than behind, 

 greatest height equal to nearly two thirds of the length ; anterior extremity broad, 

 obliquely rounded ; posterior narrowed, subtruucate, scarcely rounded ; dorsal margin 

 sloping steeply, and slightly arched ; inferior somewhat convex and with a slight sinuation 

 towards each extremity. Dorsal aspect broadly ovate, widest behind the middle, width 

 nearly equal to the height ; extremities produced into two broad mucronate processes. 

 End view very tumid, ovate, width and height about equal. Surface of tlie shell 

 beautifully and sharply reticulated, the reticulations angular (hexagonal or subhexagonal) 

 and coalescing on the ventral surface so as to form longitudinal furrows ; each valve 

 forms a sort of curved alseform ridge along the ventral margin ; and there is a lai'ge 

 tubercle in the situation of the anterior hinge-joint, forming a distinct angle or 

 gibbosity. Length -^ inch (1-05 millim.). 



A few specimens only of Cythere wetherellii have occurred in the Panojycea-heA 

 (Sables inferieurs). In England it has been found by Professor Jones in the " Middle 

 Eocene " of the Isle of Wight. 



Cythere taeentina, Baird. (Plate LXIII. figs, \a-ld.) 

 Cythere turentina, Baird, Proc. Zool. Soc. 1850, Annulosa, pi. xviii. figs. 31-33. 



Carapace, as seen from the side, somewlrat wedge-shaped, much higher in front than 

 behind, the greatest height being equal to more than half the length, and situated very 

 near the anterior extremity ; anterior margin broad and obliquely rounded ; posterior 

 narrowed almost to a point; superior margin sloping steeply, especially at the hinder 

 end, very slightly arched ; inferior gently convex, with a slight sinuation near the 

 middle. The outline as seen from above is rhomboidal, the extremities truncate ; the 



