T. Davidson ^ G. Maw — U. Silurian Hocks of Shropshire. 105 



of the Geological Society of London, vol. xix, p. 229. The upper 

 part of their section given at p. 232 appears to refer to the base 

 of an outlier of the Coal-measures, and the remainder to the base of 

 the Old Eed Sandstone and top of the Upper Ludlow. The red 

 micaceous marls in the road-cutting on the Bridgnorth side of the 

 valley clearly belong to the Old Eed Sandstone, and these are, we 

 suppose, represented by the bed " c " in Messrs. Eoberts and 

 Eandall's section. Below this the section is described as follows : — 



ft. ins. 



d. Light- coloured grits, with plant-remains 20 



e. Hard micaceous grits, somewhat flaggy, and charged with fish 



remains (" The Upper Bone Bed.") 7 



/. Flagstones bearing ciurrent markings 1 9 



ff. Micaceous sandy grits with Lingiilce 11 



h. Greenish irregularly laminated rock with conglomerate 1 



i. Hard calcareous grit with thickly disseminated greenish grains and 



many broken Lingulce 1 



Ti. Laminated light grey micaceous and sandy shales 20 



I. Grey micaceous grits 6 



m. Micaceous sandy clays coloured by peroxide of iron 6 



n. Yellow sandstones (Downton series), with Beyrichia, Lingulce, and 

 including two or more ferruginous bands, containing large quantities 

 of the dermal studs of Thelodus, fragments of LingulcB, and minute 

 crystals of quartz. Clusters of iModiolo2}sis complanata occur at the 



base of this rock (The Lower or Ludlow Bone Bed) 8 



0. Hard calcareous shales with fish-remains, Lingulce, etc 6 



p. Flaggy beds of impure limestone, with SerpuUfes longissimus, true 



Upper Ludlow 4 



g. Hard impure limestone, Aymestry series, at base. 



These are without doubt the passage-beds connecting the Devonian 

 and Silurian series ; and the only exception we take to Messrs. 

 Eoberts and Eandall's determination is the supposed occurrence of 

 Aymestry Limestone at the base of their section, as, judging from 

 the thickness of the Upper Ludlow Beds in neighbouring sections, 

 it is improbable that the Aymestry Limestone would come within 

 the section here exposed. 



Of Brachiopoda, we believe no species have been found in the 

 Linley Brook section, except Lingtda cornea, which is abundant. 



General BesuUs of the Washings. — The extensive washings and 

 hand-picking from rocks and shales of the Wenlock and Ludlow 

 series in Shropshire has enabled us to ascertain to what horizon each 

 species is peculiar or what was its stratigraphical range. Of course 

 we limit our conjectures to those species of which we have positively 

 ascertained the presence in each horizon. Some few of them may 

 perhaps occur in horizons not indicated in our table, but as they 

 have not come to our knowledge are necessarily omitted. 



A glance at our table will show that species were more numerous 

 during the Wenlock than the Ludlow period, that is to say, that 

 while 66 species have been collected from the Wenlock series of 

 Shropshire, only 37 were found in that of the Ludlow period — 22 

 being common to both epochs. These numbers are the result of our 

 personal investigations, but may be slightly modified hereafter or 

 upon still more extended research. 



