Tlie Silurian Rocks of May Bill. 743" 



The Woolhope Limestone is never thick, and fossils in it are very 

 few. The Wenlock Shales and Limestone show a normal develop- 

 ment. The latter is very fossiliferous, and shows coral-masses in 

 'the position of growth. 



The Ludlow Beds are, in the main, of a brown sandy nature. 

 No Aymestry Limestone is present, and the Ludlow Beds cannot 

 be separated into an upper and a lower division. A bone-bed is seen 

 at the top of the Ludlow Beds hv the side of the road near Blaisdon. 

 This was described by H. E. Strickland in 1863, who saw it in the 

 railway-cutting close by. 



Downton Sandstone occurs in the north of the district, where it 

 is about 300 feet thick; but it is only some 11 feet thick near 

 Blaisdon on the south. It is conformably overlain by Old Red 

 Sandstone. 



The Silurian rocks are arranged in an anticline in the part of the 

 district where May Hill is, but elsewhere show no such arrange- 

 ment. On the north they are much broken by faults. Near 

 Flaxley, in the extreme south, rocks from the "Wenlock Shale to 

 the Old Red Sandstone inclusive are overfolded. 



Dr. F. R. C. Reed describes a new species of LicJias from the 

 Wenlock Limestone and a new variety of Ccdymene papillata. 



2. ' The Petrography of the Millstone Grit Series of Yorkshire.' 

 By Albert GiUigan, D.Sc, B.Sc, F.G.S. 



Since the pioneer work of Sorb}^ on this subject, published in 

 1859, the clastic deposits of the Carboniferous S}^stem have been 

 unaccountably neglected by petrologists. The author has followed 

 the usual methods of investigation, and has collected a large 

 number of pebbles and specimens from widely - separated areas 

 which have been examined microscopically. Numerous separations 

 of the heavy minerals have also been made from all types of rock, 

 varying from coarse conglomerates to shales, which occur in the 

 series. 



Quartz-pebbles are dominant, and vary much, both in size and 

 in colour. The largest are found in the coarse-grained beds at the 

 bottom and top of the series. They often show double-sphenoid 

 forms suggestive of derivation from mechanically-deformed rocks, 

 which inference is shown to be correct by the undulose extinction, 

 the crenulate and mylonized structure seen when sections of them 

 are examined in polarized light. 



Blue and opalescent quartz is very common, containing inclusions 

 often of indeterminable character arranged in streams or rows ; 

 others contain liquid with movable bubbles, while needles ami hair- 

 like inclusions are also usually present. The quartz of the finer 

 material is similar in character, and the inclusions in the grains 

 suggest that it has been originally derived for the greater part from 

 such rocks as gneisses and schists. 



Felspar-pebbles are abundant in all the coarse beds. They 

 are dominantly microcline or microcline-mieroperthite, and, when 



