Palaeozoic Bivalved Enlomostraca. 179 



capacity) • and there are some few where the regularity of 

 their surface is interfered with by one or more lobe-like swel- 

 lings. In this feature it resembles K. Schrenkii, Keyser- 

 ling* ; but the latter has a rounded, and not ridged, ventral 

 margin. 



The ventral rims vary in development, and are apparently 

 largest in old individuals. In some cases the mesh-walls on 

 the reticulated surface show a tendency to run in faint riblets 

 within and parallel to the marginal ridges. 



The reticulation of the surface is relatively large, in most 

 cases with a more or less angular form of mesh, and is very 

 beautiful in well-preserved specimens. 



The subcentral spot is often obsolete or not to be seen. 



Kirkbya permiana is of common occurrence in the marine 

 shales of the Carboniferous-Limestone series of Scotland and 

 the north of England. It is found in a similar shale in the 

 upper portion of the Calciferous Sandstone of Fife. 



As a Permian species it is met with in the Magnesian 

 Limestone of Durham and Yorkshire, also in Germany. 



Some of its British localities are as follows : — ■ 



Scotland. Calciferous Sandstone : coast west of Pitten- 

 weem, Fife. Carboniferous Limestone (Lower) : Brockley, 

 Calderside Quarry, Brankumhall Quarry, in Lanarkshire ; 

 Galabraes, Whitebaulks, in Linlithgowshire ; Corrieburn, 

 Scullengour, Craigenglen, in Stirlingshire ; Fullerton, Currie- 

 lee Lime- works, Darcy Limestone Quarry, Magazine Lime- 

 works, Hillhead Quarry, near Cockmuir Bridge, in Edin- 

 burghshire ; Catcraig, near Dunbar, Burlage Quarry, East 

 Salton, in East Lothian ; coast near Abden, Glenniston 

 Quarry, Inverteil Quarry, Ladedda Quarry, Wilkieson, Cults, 

 Teasses, in Fife ; Carlops, Whitefield, in Peeblesshire. Car- 

 boniferous Limestone (Upper) : Robroystone, Orchard, Ken- 

 nox Water, Auchenbeg, in Lanarkshire ; River Avon below 

 Kinneil, in Linlithgowshire ; &c. 



England. Carboniferous-Limestone series : Scremerston, 

 Ridsdalef, Ancroft, in Northumberland ; Barnard Castle, Dur- 

 ham ; Wyebourne, Calees, in Cumberland ; in the Scar 

 Limestone at Stainton Quarry, Lancashire. 



As a "recurrent" in Permian strata it is found in the 

 following localities : — 



In Lower Magnesian Limestone : Westoe, Eldon, East 

 Thickley, Walworth, Morton Tinmouth, Summerhouse, and 



* In Schrenk'a ' Keise Nordost. Russl.' &c. 1S54, p. 112, pi. 4. fig. 37. 



+ Mr. (J. Ji. Vine quotes this species, also K. umbonata and bvpartvta, 

 from Ridsdale, and from Hurst, Yorkshire (Proc. Yorksh. Geol. Polyt. 

 Soc. for 1883, p. 237). 



