84 Geological Society : — 



December 5, 1855. — W. J. Hamilton, Esq., President, in the 

 Chair. 



The following communications were read : — 



1. " On the Tllestones, or Downton Sandstones, in the neigh- 

 bourhood of Kington, and their contents." By R.W. Banks, Esq. 

 Communicated by Sir R. I. Murchison, V.P.G.S. 



In the Bradnor Quarry near Kington, on the borders of Radnor- 

 shire and Herefordshire, the Tilestones and Downton Sandstone are 

 seen to overlie the Ludlow rock in the following descending order : 

 — 1. thin tilestone ; 2. wall-stone, 12 feet thick, unfossiliferous ; 

 3. mud?tone, 3 to 6 inches, coloured grey by the intermixture of 

 vegetable matter, and containing fragments oi Pterygotus, and other 

 crustacean remains, together with fossils allied to Cephalasfis LyeUii 

 and C. Lcwisii {Ag&s.); '4. Downton sandstone, 3 to 4 feet, with 

 Lingula cornea, Trochus helicites, Pterijyotus, and Cephalaspis-like 

 fossils as above; 5. another grey mudstone, similar in character and 

 contents to No. 3 ; 6. yellow sandstone and flagstone, 4 feet, with 

 the Cephalaspis-like fossils, Pterygotus, Leptocheles, and Trochus 

 helicites ; 7. Ludlow rock. Another section in the neighbourhood 

 exhibits thin shaly beds of tilestone, with Lingula cornea, underlaid 

 by layers of flattened Orthonota amygdalina and Trochus helicites, 

 which rest on the equivalent of the Ludlow bone-bed, here about 

 2 or 3 inches thick, and containing Ortlioceras gregurium, O.politum, 

 Goniophora cymhceformis, Orthonota amygdalina, Orhicula rugata, 

 Holopella, Chonetes lata, Cornulites serpularixis, Cucullella antiqua, 

 Modiolopsis Icevis, Rhynchonella, Bellerophon carinatus, Leptocheles, 

 Onchus tenuistriatus, Sphagodus, and SerpuUtes. 



The organic remains of these tilestone, sandstone, and mudstone 

 beds were illustrated by numerous highly finished drawings by the 

 author ; and these, together with his descriptive notes, indicated 

 the existence of one or more hitherto unknown or little understood 

 forms of Crustacean life, probably of the EurypteridcB group, and 

 elucidated several important characters in the carapace and append- 

 ages of the Pterygotus ; with regard to which genus, Mr. Banks 

 finds reason to differ from the generally received opinion that it was 

 allied to Limulus and the Poecilopods. 



Mr. Banks's specimens of the fossils resembling Cephalaspis Lyellii 

 and C. Leioisii offer considerable evidence towards invalidating the 

 Ichthyic relationship of these fossils, and placing them amongst the 

 Crustacea. 



In conclusion — from the absence of the numerous Mollusca cha- 

 racteristic of the Ludlow rocks, and from the presence of Crustacea 

 that have not been found in the Ludlow beds, and especially the 

 abundance of the Pterygotus, so characteristic of the Middle Old 

 Red of Scotland, — the author is inclined to separate these Downton 

 or Tilestone beds from the Upper Ludlow Rocks, and class them (as 

 Sir Roderick Murchison, previously to his later remarks on the sub- 

 ject, originally arranged them) as the bottom-beds of the Old Red 

 Sandstone. 



