6k REPORT 1865. 



yielded some of the mo3t interesting and beautiful of the organic remains of the 

 Upper Silurian rocks. 



Its relative position may be seen by reference to the Geological Survey, Hori- 

 zontal Sections, sheet 24, section 2. 



There is no good natural section of it, but it has been exposed at several places 

 by sinkings and excavations, and is now seen in a cutting at the Dudley Railway 

 Station. In the same cutting, near the Trindle, there formerly existed a section 

 showing the coal-measures resting on the shale, and showing also a cliff* in the 

 shale, but that section has been obscured or destroyed ; it is, however, well- 

 figured in Prof. Jukes's 'South Staffordshire Coal-field.' 



By some authorities this shale is classed as Ludlow, by others as Wenlock. 



Sir R. I. Murchison in ' Siluria,' Mr. Salter in his 'British Trilobites,' and the 

 Dudley Geological Society, in their Reports, have placed it in the Ludlow series. 



Prof. Jukes, in his ' South Staffordshire Coal-field,' mentions it as belonging to 

 the Ludlow, but in another part of the same work shows it to belong to the Wenlock. 



The Geological Survey Map and Sections have it coloured as Wenlock shale, 

 excepting a recent edition, in which it is coloured as Lower Ludlow. 



In the Jermyn Street Catalogue, lately published, the localities of the Silurian 

 fossils from the Dudley rocks, including those from the shale in question, are 

 given as Wenlock. And Prof. Morris, in his ' List,' published in the first volume 

 of the 'Geologist,' gives the "localities and fossils of the Lower Ludlow," but 

 does not include Dudley or the Dudley shale in his " localities," nor the charac- 

 teristic species of this shale in his "fossils." Of its many Trilobites, not one 

 is shown. 



In ' Siluria ' it is stated that " from the physical relations of this shale, and from 

 its forming usually a part of the same hills as the mass of the Ludlow rocks, it is 

 classed with that formation ; though in reality it is only an intermediate band 

 intimately uniting the Wenlock and Ludlow, and is almost equally connected with 

 both by structure and fossil contents." 



As to fossil contents, the materials for examination have greatly increased since 

 the passage in ' Siluria,' above quoted, was written. The fossils from the Upper 

 Shale then available would be derived principally from one locality only, 

 and consisted, for the most part, of species of the classes Lamellibranchiata and 

 Cephalopoda, in which the Ludlow rocks are so prolific, but of which many are 

 found also in the Wenlock limestone. Besides these, however, this shale, examined 

 in other places, is found to contain most of the Zoophyta, Crustacea, Biyozoa, 

 Brachiopoda, and Gasteropoda, all so common in the Wenlock limestone below it, 

 but so meagrely represented in the tj'pical Lower Ludlow rocks of the Ludlow 

 district. 



In illustration of this, lists of the principal fossils are appended ; a summary of 

 which shows that of Cobals this Upper Shale has twenty seven species, of which 

 twenty-three are found in the limestone below ; but none of them are fomid in the 

 typical Lower Ludlow rocks of the Ludlow district. 



Of Trilobites, the Upper Shale has twenty species and subspecies, fourteen of 

 which are also in the limestone below. The Lower Ludlow of Ludlow district 

 has eight species, four of which are also in the Upper Shale and the Wenlock 

 limestone ; and of the remaining species, three are in the Upper Shale, but not in 

 the limestone. 



Of the Brachiopoda, the Upper Shale has twenty-nine species, twenty-four of 

 which are also found in the limestone below. The Lower Ludlow of Ludlow has 

 ten species, of which six are common to the limestone, Upper Shale, and Lower 

 Ludlow, and two of them to the Upper Shale. 



Does it not thus appear that the fauna of this shale has, on the whole, a closer 

 relationship to that of the Wenlock limestone below it, than to that of the Ludlow 

 rocks above ? 



The highest authorities — both Sir R. Murchison and Prof. Jukes — consider 

 this shale to be lithologically undistinguishable from that below the limestone. 



And while it overlies, and is conformable to the Wenlock limestone, it is not 

 found to have any of the Ludlow beds deposited upon it. This is clearly shown 

 in Jukes's 'South Staffordshire Coal-field,' thus: — "The uppermost member of 



