1868,] HARKNESS AND NICHOLSON CONISTON GROUP. 301 



represented by calcareous shales ; and in these latter are found very 

 characteristic Caradoc fossils. 



In the neighbourliood of Sedbergh, Mr. Hughes gives the fol- 

 lowing as occurring in these calcareous shales : — Petraia suOduplicata, 

 var. crenulata, Eiicrinites, Phacops apiculatusl, species of Phacops, 

 Trinucleus concentricus, Orthis hiforata, 0. calligramma, Stropho- 

 mena dejyressa, S. alternata, and species of Orthoceras. 



The succeeding and conformable mudstones introduce an entirely 

 new fauna, and one which has no representative in Great Britain 

 among rocks appertaining to the Caradoc age. These rocks afford 

 six species of the genus Diplograpsus, all of which, except D. tereti- 

 uscidas, which has recently been obtained from the Caradoc rocks of 

 Haverfordwest, are characteristic Upper Llandeilo forms. 



Of the genus Graptolites, the species from these mudstones (with 

 the exception of three, O. SedgwicMi, G. priodon, and G. tenuis, 

 and the new forms) are also equally confined elsewhere in Great 

 Britain to the Upper Llandeilo rocks; and another form, Ras- 

 trites perecp'inus, also has hitherto been found in Britain only in 

 the same horizon. Nearly the whole of the Graptolites, except the 

 new species, of the mudstones above the Coniston limestone are of 

 such forms as are most abundant in the black shales of Dumfries- 

 shire. 



Some of the species which are found in the Dumfriesshire shales 

 have as yet not been met with in the mudstones ; and the twin 

 Graptolites, the Didymograpsi, which are represented in Dumfries- 

 shire by several forms, seem to be entirely absent from the Coniston 

 mudstones. The Upper-Llandeilo position of the Dumfriesshire 

 graptolitiferous shales is marked by the occurrence of Siplionotreta 

 micula ; while, as regards fossil evidence, the Caradoc age of the 

 mudstones is shown by the presence in them of Sphceronites punc- 

 tatiis and Orthis ccdligramma. 



Although most of the Graptolites which have been obtained from 

 the Coniston mudstones have previously been found in Great Britain 

 in strata no higher than the Upper Llandeilo rocks, the case is 

 somewhat different as regards Ireland. The Caradoc beds of Po- 

 meroy yielded several of these species many years ago to the late 

 General Portlock ; and more recently the officers of the Irish Geolo- 

 gical Survey have procured in other portions of Ireland, w^here strata 

 of the Caradoc age occur, forms of Graptolites which are usually 

 looked upon as marking the Llandeilo group. Two of these localities 

 maybe cited — one atTramore, county Waterford, where, in black shale, 

 underlying a calcareous flagstone with abundance of Caradoc fossils, 

 the following species have been recognized by Mr. Baily, CaUograpsus 

 elegans, Hall, Dendrograpsus jlexuosus, Hall, Diplograpsus pristis, 

 Didymograpsus sextans, Graptolites tenuis, and G. priodon*. The 

 other is in the county Clare, where the following occur, Didymo- 

 grapsus Forclihamrtieri, Geinitz, D. Jiamatus, Baily, Diplograpsus 

 pristis, D. tnucronatus, Graptolites gracilis, Hall, G. Nilssoni, G. 



* Explanations to the sheets of the Irish Geol. Survey, No. 167, 168, 178, and 

 179, p. 20. 



