Paloeozoic Bivalved Entomostraca. 257 



rapidly inward beneath ; posterior extremity higher and 

 sloping- as rapidly outward until it sweeps round to the front 

 to form a short, convex, ventral margin ; right valve overlap- 

 ping the other moderately ; surface smooth. Length -^ inch. 

 It is convenient to treat this as a species. It was figured, 

 as above quoted, from a Bavarian example. We now give a 

 figure of a specimen from the Scar Limestone of Arnside. 

 It also occurs at Back Burn, Plashetts, Northumberland, 

 Weston-super-Mare, Somerset, and other places. 



18. BeyricMa radiata, J. & K. 

 (PI. VIII. figs. 1, 2 a, 2 h.) 



BeyricMa radiata, J. & K., MS. 1867, Trans. Geol. Soc. Glasgow, 

 vol. ii. p. 220. 



Subrhomboidal in outline, highest in front ; dorsal border 

 straight, ventral border convex ; valves convex, with a round 

 prominent boss rather behind the centre, and separated from 

 a small anterior boss by a deep sulcus ; a curious broad sub- 

 marginal sickle-like plate, cross-lined, so as to represent a 

 solid radiate frill, runs concentrically from the antero-dorsal 

 angle to the postero-ventral curve ; surface smooth, granu- 

 lated, or tuberculated ; shell thick. Length ^V to -^V inch. 



This strongly-marked species (discovered by Mr. John 

 Young) characterizes the Carboniferous-Limestone series and 

 upper half of the Lower Carboniferous. In the former it is 

 found at : — 



East of St. Monans, Wilkieson Quarry, Sunnybank Quarry, 

 Teasses Quarry, in Fifeshire ; East Salton, Paiston Quarry, 

 Burlage Quarry, in East Lothian ; Hillhead Quarry (Wilson- 

 town), Williamswood, Robroystone, Calderside Quarry, Bog- 

 head Quarry, in Lanarkshire j Craigenglen, Stirlingshire; 

 Orchard Quarry, Henfrewshire. 



In Calciferous Sandstone: Pittenweera, Fifeshire; Hare- 

 lawhill, Roxburghshire ; Cam Beck, Cumberland ; Plashetts, 

 Northumberland ; Kendal and north of Storr Moss (in Scar 

 Limestone) , Westmoreland. 



19. BeyricMa longispina, sp. nov. (PI. VIII. fig. 3.) 



Similar in general form to the species immediately preceding, 

 and lobed or bossed in the same way ; but with no submar- 

 ginal plate. In lieu of the latter feature are two large, 

 curved, ventral spines, which are tubular (?) and always 

 placed in the same position — one towards each extremity. 

 Length ^^ inch. 



