1808.] NTCUOLSOX CONISTON-FT.AO GRAPTOLITKS. 54H 



Barr., O. llcemeri, Barr., and O. colonus, Barr, In the upper zone, 

 besides all the above, there occur G. lohiferus, M'Coy, G. Nihsoni, 

 Barr., G. SedgwicJcii, Portl. (= G. sj)iralis, Gein., and G. proteus^ 

 Barr.), G» turnculatus, BaiT., Diployrapsus paJmeus, Barr., liastrites 

 peregriniiSy Barr., R. Linncel, Barr., RetloUtes Gelnitzumus, Barr., 

 and other species. From the above lists, even were there nothing 

 else to go by, we should be certainly inclined to believe that M. 

 Barrande was in error in separating the two Graptolitiferous zones, and 

 in placing the higher one(etageE) at the base of the Upper Silurian 

 series. The species G. lobiferus, G. Nilssoni, and G. SechjivicJcii, with 

 Diplograpsus palmeus and the two species of liastrites, are all found 

 in the Upper Llandeilo rocks of Dumfriesshire ; whilst the genera 

 Dlplograpsus and Rastrites have never been proved, as yet, to tran- 

 scend the limits of Lower Silurian rocks. These facts are of them- 

 selves sufficient to render it highly probable that etage E is truly of 

 Lower Silurian age ; and an examination of the Graptolites of the 

 Coniston Flags makes this conclusion almost inevitable. In the 

 Coniston Flags, namely (and this of itself is a singular fact), there 

 occur all the Bohemian species above mentioned as characteristic of 

 the upper zone, or etage E, of Barrande. Some of these, too, are 

 very peculiar and local in their distribution, such as G. Bohemicus, 

 Barr., G. turricidatus, Barr., and Retiolites Geinitzianus, Barr. Not 

 only is this so, but these same species are found in the Flags to be 

 coexistent with several familiar Upper- Llandeilo and Caradoc spe- 

 cies, such as Climacograpsus teretiusculus, ^i^., Dlplograpsus pristis, 

 His., D. angustifolius, Hall, and D. tamariscus, Mch. In fact, out 

 of the twenty-four species of Graptolites from the Coniston Flags, if 

 we except five new species as useless for purposes of classification, 

 we find twelve out of the remaining nineteen, or more than three - 

 fifths of the whole, to be common to the Flags and to Barrande's 

 etage E. From these facts we are justified in coming to the con- 

 clusion that the main Graptolitiferous zone of Bohemia (etage E) is 

 homotaxeous, if not strictly cotemporaneous, with the Coniston Flags 

 of Cumberland and Westmoreland, and that both are truly of Lower- 

 Silurian age. 



A decided relation, though not nearly so marked a one, can also 

 be shown to exist between the Coniston Flags and the Hudson -River 

 group and Utica Slates of America. Five species, at any rate, are 

 common to the two formations, viz. Climacograpsus te7'etiusculus, 

 Graptolites Sagittarius, Dlplograpsus pristis, D. angustifolius, and D. 

 putillus, of which the last two were first described from American 

 specimens. As the Hudson-River group is of Caradoc age, an addi- 

 tional corroboration is thus furnished to the view that the Coniston 

 Flags should be looked upon as a portion of the Caradoc or Bala series. 



EXPLANATION OF PLATES XIX. & XX. 



Plate XIX. 



Fig. 1. Dlplograpsus 2>alf^eus, Barr., ordinary form, natural size. From the 

 Upper Llandeilo shales of Dumfriesshire. 

 VOL. XXIV.^ PAKT I. 2 P 



