OF THE CULM OF DEVON. 59 



Notes on the Discoveey oe Trilobites in the Culm-Shales of South-East 



Devonshire. 



Although the Culm-deposits of Devonshire have long been known and studied, 

 it has been a matter of considerable doubt as to the exact horizon which they 

 really occupy. The Geological Surveyors have, it is true, spent much time in 

 re-examining certain parts of the county, but owing to the smallness of the scale 

 of the Ordnance Survey map (only one inch to the mile), and the inaccuracy of 

 the topography, but little could be done to show the detailed work resulting 

 from these later investigations. 



Prof. J. Beete Jukes, F.R.S. (' Quart. Journ. Geol. Soc.,' 1866, pp. 320—371), 

 and subsequently Mr. R. Etheridge, F.R.S. (op. cit., 1867, pp. 568—698), 

 described the whole of the northern portion of the county afresh, whilst Mr. 

 Horace B. Woodward, F.G.S., Mr. Clement Reid, F.G.S., Mr. W. A. E. Ussher, 

 F.G.S., as representing the Geological Survey, have been engaged upon the more 

 southern parts. Added to this Dr. Harvey B. Holl, F.G.S., Mr. A. Champer- 

 nowne, F.G.S., and Mr. Jno. E. Lee, F.G.S., have contributed not a little to the 

 elucidation of difficult parts of the Geology of South-Eastern Devon, whilst Mr. 

 Townshend Hall, F.G.S., has done equally useful work in the northern area. 



1839. — Sir H. T. dela Beche 1 notices the Culm-formation, and intimates (p. 117) 

 that Prof. J. Phillips regarded the shale-fossils as belonging to the Carboniferous 

 Limestone. 2 The list of plants which he gives contains a mixture of species, but 

 many of those quoted are probably true Coal-Measure plants which do not occur 

 in the Culm proper. 3 



1840. — Prof. Sedgwick and Sir R. I. Murchison in their memoir " On the 



1 'Beport on the Geology of Cornwall, Devon, and "West Somerset,' 1S39. See also 'Trans. 

 Geol. Soc.,' 2nd series, vol. iii, p. 163. 



2 Judging from the apparent dip of the Culm-Measures beneath the Devonian rocks at Chudleigh, 

 Sir H. de la Beche considered that this Limestone (which is now proved by its fossils to be the 

 Qoniatites intumescens Stage of the Upper Devonian, Boemer, ' Geol. Mag.,' 1880, pp. 145 — 147) 

 was included in the Carbonaceous series, and as such it was originally engraved and published in his 

 sections and coloured in the Geological Survey Map (Clement Beid, ' Geol. Mag.,' 1877, p. 454). 



8 Mr. B. Kidston, F.G.S., mentions (in a letter to the author) the following plants as determined 

 by him from the Culm, viz. : 



Asterocalamites scrobiculatus, Schlot., sp. Lepidophloios, sp. 



(= Bornia radiata, Brong.). Halonia (fruiting branch of Lepidophloios). 



Calamites Roemeri, Gopp. Sigillaria {?). 



Sphenopteris, sp. nov. Stigmaria ficoides, Brongt. 

 Lepidodendron Bhodeanum (?), Sternb. 



" All these plants," he adds, " have a ' Calciferous Sandstone ' facies, and are equivalent to the 

 ' Culm ' of Germany." 



