THE SHELL-LIMESTONE OF DURHAM. 163 



Bairdia ampla, Eeuss. " Jahresb. Wetter. Ges. 

 1854," p. 68, figs. 7a, 7b. 

 Carapace irregularly ovate, showing but little of the trian- 

 gularity of the i?azVc?/GP; dorsal margin rounded; ventral 

 slightly sinuous ; extremities obtusely angular. The 

 plumpness and large size of the carapace well deserve the 

 name adopted by Dr. Reuss for this species. 

 It occurs at Byers' Quarry. It has been collected by Mr. 

 Kirkby from the magnesian limestone of Hampole, Yorkshire. 

 Professor Reuss had it from the Zechstein of the Wetterau. 



13. C. {Bairdia) gracilis, M'Coy{?). PI. XL, fig. 15. 



Bairdia gracilis, M'Coy. " Syn. Char. Carb. Foss.," 



p. 164, pi. 23, fig. 7. 

 Bairdia gracilis, Jones, in " King's Monog, Perm. 



Foss.," p. 63, pi. 18, fig. 7. 

 Bairdia gracilis, Reuss. " Jahresb. Wetter. Ges. 



1854," p, 65, fig. 2a, 2b. 

 Bairdia gracilis, Richter. " Zeitschrift Dent. Geol. 

 Ges.," vol. vii., p. 530, pi. 26, figs. 16, 17. 

 A cast (from Byers' Quarry), much worn, of a carapace nearly 

 allied to B. plebeia, but very much narrower ; probably Professor 

 M' Coy's B. gracilis. 



A form like this has been found in the German Zechstein by 

 Professor Reuss and Dr. Richter. 



14. C. {Bairdial) acuta, Jones. PI. XI., fig. 16. 



Cythere {Bairdia ?) acuta. Jones, in " King's Monog. 

 Perm. Foss.," p. 63, pL 18, fig. 10. 

 Carapace sub-triangular, smooth, convex ; dorsal border 

 rounded, produced; ventral nearly straight; extremities 

 acute. 

 From Byers' Quarry. Not very rare. 



Mr. Kirkby believes that he has met with this species at 

 Tunstall Hill. 



We add a table of Permian Entomostraca, in which are in- 

 cluded those species not found in England ; the latter are reduced 

 to the nomenclatorial system adopted in the preceding papers. 



