68 Mr Marr, On the Phacopidae of the Lake District. p\Iay 21, 



The Basement Bed is thus either a calcareous conglomerate, 

 as at Austwick and near Sedbergh, or a limestone sometimes 

 with a brecciated structure, as at Crag Hill, or a calcareous 

 sandstone or mudstone as at Spengill and Skelgill, or a concre- 

 tionary bed in which evidently much chemical change has been 

 going on, as at Ash Gill. It is almost always full of pyrites. 

 He paralleled the Coniston Flags and Grits with the Denbigh 

 Grits and Flags; the Pale Slates with the Tarannon Shale and 

 Pale Slates of Wales ; the Graptolithic Mudstones with the 

 banded beds of Aberhirnant, &c., and the Basement Bed with 

 the Corwen Grit and conglomerate and with the Limestone of 

 Llansantfraidglynceiriog. He gave lists of fossils, pointing out 

 that, as far as his observation had gone, Cardiola interrupta never 

 occurred below the Coniston Flags, nor Trinucleus above the 

 Bala Beds ; while Meristella crassa was as yet peculiar to the 

 Basement Bed. It was found at Spengill ; in the Corwen Grits 

 of Cyrnybrain: in the Llandovery Rocks at Llandovery; and, 

 according to the survey, in the equivalent beds in other districts. 



Note on the Phacopidae of the Lake District, by J. E. Makr, 

 S. John's Coll. 



The author considered the Phacopidae peculiarly adapted to 

 shew the palseontological differences between the Cambrian and 

 Silurian of the Lake District ; 1st, on account of their occurrence 

 all through the series ; and, 2ndly, on account of the limitation of 

 each species, so far as yet known, to small thicknesses of strata. 



He gave the following list of the more important species, with 

 the beds which they characterise : 



Zone of 



' Kirkby Moor Flags "i 



Bannisdale Slates f Phacops (Acaste) Downingiae. 



Couiston Grits ^ 



Silurian .. ^ Coniston Flags Phacops (Odontoclaeile) obtusicaudatus. 



Pale Slates 



Graptolithic Mudstones . . Phacops (Phacops) Musheni ? 

 Basement bed of Silurian 



r Upper Bala Shales j Phacops (Odontocheile) mucronatus var. 



^^ { Phacops (Acaste) apiculatus. 



Cambrian J Coniston Limestone \ PJacops (Chasmops) conophthalmus. 



^ ( Phacops (Chasmops) macroura. 



Green Slates (No fossils). 



l^ Skiddaw Slates Phacops (Acaste) Nicholsoni. 



Keferring to the above list he observed that the two forms of 

 Phacops most common in the Coniston Limestone belonged to the 

 subgenus Chasmops, a Cambrian subgenus ; that the two species 

 found in the overlying Upper Bala Shales were of great interest. 



