EXPLANATION OF PLATES. 169 



Fig. ob Kirkhya Permiana^ perfect carapace, dorsal aspect. 

 be „ „ perfect carapace, ventral aspect, 



od „ „ perfect carapace, end-view, showing the mode of 



overlap. 

 oe „ „ reticulation, magnified 50 diameters. 



5/ „ ,T oval spot, magnified 50 diameters. 



6a „ „ left valve, not well preserved. From Byers' 



Quarry. 

 6& „ „ left valve, edge-view. 



7 „ „ \ax. glypta: right YdlvQ. From Byers' Quarry. 



8« „ „ var. Richteriana, Jones: left valve. From Saalfeld. 



85 „ „ var. Richteriana: part of surface with punctated 



ridge and oval spot, magnified 50 diameters. 

 9« „ „ var.i2oess«^eW,Reuss: right valve. I Copied from 



96 „ ,, edge-view J Reuss's plate. 



EXPLANATION OE PLATE IX. 



Fig. 1 Bairdia plebeia^ Reuss: right valve, magnified 23 



diameters. 

 2 B, plebeia: left valve of another form, magnified 23 



diameters. 

 2a Lateral contour, with contact-line of ventral margins. 



4 & 4a B. plebeia, var. ehngata: magnified 23 diameters. 



3 & 3a B. plebeia, var. ventricosa: right valve, magnified 28 



diameters. 



5 & 5a B. plebeia, var. Neptuni: left valve, [magnified 25 



diameters. 



6 & 6a B. plebeia, var. Reussiana: right valve, magnified 26 



diameters. 

 9, 9a, 10, 12, & 1 2a, B. plebeia, var. caudata: right valve, magnified 28 



diameters. 

 11 & 11a B. plebeia, var. amygdalina: left valve, magnified 28 



diameters. 

 8 & 8a Bair-dia, Kingii, Reuss: right valve, magnified 34 



diameters. 



7 & 7a B. Kingii, var. compressa: right valve, magnified 25 



diameters. 



13 & 13a Cytkere subreniformis, Kirkby : right valve, magnified 



40 diameters. 



14 & 14a Bairdia Schaurothiana, Kirkby: left valve, magnified 



28 diameters. 



15 & 15a Bairdia Berniciensis, Kirkby: right valve, magnified 



33 diameters. 

 All from the shell-limestone of Tunstall Hill. 

 VOL. IV. PT. II. W 



