or THE AJSTTWBEP CEAG. 389 



subtruncate in front, broadly rounded behind. End view very broadly subovate, emar- 

 ginate in the middle both at base and apex. Surface of the shell irregularly furrowed 

 or undulated in a transverse direction, and marked with distant pittings, which have a 

 tendency to follow the lines of the furrows. Length -^ inch (0'66 millim.). 



One specimen only of this very distinct species has occurred in the Sables moyens 

 (zone a Bryozoaires). 



Ctthere limicola (Norman). (Plate LXIV. figs. 9 a, 9 b.) 

 Cyfhereis limicola, Norman^ Nat. -Hist. Trans. Northumberland & Durham, vol. i. p. 20^ pi. vi. 



figs. 1-4 (1865). 

 Cythere nodosa, G. O. Sars, Oversigi af Norges marine Ostrac. p. 34 (1865). 

 Cythere areolata, Brady, Trans. Zool. Soc. Lond. vol. v. p. 381, pi. Ixii. figs. 2 a-d (1865). 

 Cythere complexa, Brady, Brit. -Assoc. Keport, p. 210 (1866) . 

 Cythere limicola, Brady, Monog. Recent Brit. Ostrac. p. 405, pi. xxxi. figs. 38-il, 43-46 ; Brady, 



Crosskey, and Robertson, Monog. Post-tert. Entom. of Scotland, &c., p. 154, pi. x. figs. 1-4. 



Carapace, as seen from the side, subtrapezoidal, rather higher in front than behind ; 

 height equal to about two thirds of the length ; anterior extremity obliquely rounded ; 

 posterior produced in the middle and excavated above ; superior margin rather concave, 

 abruptly angular at each extremity, inferior nearly straight. Seen from above, the 

 outline is boat-shaped, widest behind, tapering gently toward the front and abruptly 

 behind. End view subtriangular, base broad and flat, apex obtusely rounded, sides 

 excavated. Shell-surface uneven, rugose, often obscurely reticulated, the interstices 

 being finely punctate ; a conspicuous rounded tubercle over the anterior, and two near 

 the posterior hinge ; a strongly marked longitudinal ridge runs along the valves just 

 within the ventral margin. Length -4^5^ inch (0-54 millim.). 



One valve only found in the " Sables moyens " (zone a Isocardium cor). C. limicola 

 is tolerably common in the North Sea in a living state, and has been found in many 

 Post-tertiary deposits in Scotland, and also in Canada. 



Cttheke latimarginata, Speyer. (Plate LXIV. figs. 8 a-8 d.) 



Cythere latimarginata, Speyer, Die Ostrac. der Casseler TertiarbUd. p. 22, pi. iii. figs. Za-d (1863) ; 



Brady, Crosskey, and Robertson, Monog. Post.-Tert. Entom. of Scotland, &c., p. 163, pi. xvi. 



fig. 6. 

 Cythere abyssicola, G. O. Sars, Oversigt af Norges marine Ostr. p. 43. 



Carapace, as seen from the side, oblong, higher in front than behind ; height equal 

 to about half the length ; anterior extremity broadly rounded, posterior rounded but 

 much nari'ower ; superior margin sloping rather steeply backwards, and twice sinuated, 

 in front of and behind the middle; inferior margin rather deeply sinuated in the 

 middle. Seen from above, the outline is irregularly oval and compressed, the extremi- 

 ties being wide and truncated ; the sides only slightly convex, and marked by one or 

 two rounded protuberances. The substance of the shell is very thick and hard ; the 



3g2 



