104 SILURIAN. 



discovered by the Rev. T, T. Lewis and Dr. Lloyd. It comprises 

 a layer, from one inch to a foot in thickness, called "Gingerbread," 

 which is largely made up of remains of Fishes, Crustacea, and other 

 fossils, as well as coprolites. Some of the fish-remains are of 

 a mahogany tint or a brilliant black ; the INIollusca are many of 

 them phosphatized.^ The fish-remains include Auchcnaspis Saltcti, 

 Cephalaspis ornatus, C. Miirchisoni, Phrtrodus 7)iirabilis, Thelodus 

 paroidcns, Pteraspis Banksii, and Scaphaspis Liidensis. The Crustacea 

 include Astacodcnna, Ceratiocaris, Euryptcrus, Pterygotiis (and its 

 egg-packets known as Parka decipiens), Slimonia, Stylonurus, 

 Heniiaspis, etc. 



The Ludlow Bone-bed has been noticed not only in the neigh- 

 bourhood of Ludlow, but at Bradnor Hill, near Kington, and at 

 Linley, in Shropshire. 



Among other fossils from the Upper Ludlow Beds are remains 

 of Land-plants, belonging to the genera Actmophylliim and 

 Chondrites. Some Sponges, Corals, and Echinoderms are also 

 to be found. Among Trilobites are Calymene Blumenbachii, Encri- 

 nurus punctaius, Homalonotus Knightii, Phacops Doivnifigicp, etc. 

 The Brachiopods include Discina riigata, Orthis elegantula and var. 

 orbicularis, Chonetes striatella, Lingula lata ; Lamellibranchs include 

 Aviciila antiqua, Modiolopsis hvvis ; Gasteropods include Euomphalus 

 carinatiis, Murchisonia Lloydii, Pleiirotomaria crcnidata, etc. Several 

 species of Bellcrophon occur, also Litiiitcs gigafttfus, Orthoceras 

 bullatum, etc. The Annelides Serpnlitcs longissimus and Cornulites 

 serpularius are also met with. 



The beds are exposed at Ludlow, Ledbury, Woolhope, Malvern, Hagley and 

 Abberley, May Hill, near Usk, etc. (See Figs. 12, 13, 14, and 15.) They are 

 extensively quarried for building purposes. 



Downton Sandstones. 



The Upper Ludlow Beds are capped by sandstones which have 

 been quarried near Downton Castle, in Herefordshire, not far from 

 Ludlow. For these beds the name Downton Castle Stone was 

 used by Murchison. They consist of red, grey, and yellow 

 micaceous sandstones, and attain a thickness of from 80 to 100 

 feet. Together with the Ledbury Shales, they form the Passage- 

 beds between the Silurian system and the Old Red Sandstone, and 

 in some respects may be said to belong as much to one formation 

 as to the other. 



These passage-beds were first observed by Murchison at Hay, 

 in Brecknockshire, and in 1834 he grouped them under the name 

 of ' Tilestone,' at the base of the Old Red Sandstone. The term 

 Tilestone was subsequently abandoned by Murchison, for although 



1 Murchison, Siluria, edit. 5, p. 133; Dr. J. Harley, Q. J. xvii. 542; H. E. 

 Strickland, Q. J. viii. 383, ix. 8. The term Coprolites means, literally, petrified 

 dung or fajces ; it is, however, often applied simply to phosphatic nodules. 



