Correspondence — Mr. W. A. E. JJssher. 93 



no surprise in the Arctic Kegions, provided a suitable temperature 

 were provided for them. 1 



I cannot give here all the details explained in my paper, but I 

 claim to have surrounded the North Pole with such a network of 

 Lombardic plants, requiring Lombardic heat, but not Lombardic 

 light, as to render the escape of the Pole from its present position as 

 difficult as that of a "rat in a trap surrounded by terriers." 



If the Lombardic light as well as heat were present in these 

 Tertiary times, it would be difficult to explain the absence of a 

 multitude of evergreen plants which require light to develope 

 chlorophyll grains. Such evergreen plants ought to have migrated 

 from North America and Europe into Greenland as easily and as 

 rapidly as the peculiar groups of evergreens found there in Tertiary 

 times. 



In my opinion, the natural selection in the Tertiary Flora of 

 Greenland of such evergreens only as require Lombardic heat, but 

 can dispense with Lombardic light, is a fact which my opponents in 

 the Geological Section not only did not answer, but entirely failed 

 even to see the force of. S. Haughton. 



Trinity College, Dublin, \7th January, 1879. 



FACTA NON VEEBA. 



Sir, — The Devonian question being already hampered with so 

 much theory, I venture to hope that you will insert the following 

 facts, arrived at after a series of traverses by almost all the river- 

 courses in North Devon. Prof. Hull's description of the rocks of 

 this county and West Somerset contains serious errors, into which I 

 am sure he would not have fallen had he been acquainted with the 

 area. 



Firstly. The Pilton beds consist of bluish grey and grey schistose 

 and slaty rocks, with local developments of grey and brownish grit. 

 The calcareous element is represented by thin, trivial, and impersis- 

 tent beds of limestone. 



Secondly. The Baggy Sandstones are buff-grey and brown, 

 apparently confined to a definite horizon, but by no means equally 

 developed thereon ; they rest upon olive slates. For stratigraphical 

 survey lines these may be included in the Pilton beds, from which 

 they cannot, in disturbed districts, be readily distinguished. 



Thirdly. The Pickwell Down beds are strangely mixed up with 

 the Morthoe Slates in Prof. Hull's table, which would be fatal to the 

 supposition of unconformity between them (vide Geol. Mag., 1878, 

 p. 531, lines 18 and 19). The Pickwell Down series is distin- 

 guishable through North Devon by its characteristic interstratification 

 of slates, not shales ; these are almost invariably lilac or purple, and 

 toward the base of the division seem to pass into the Morte group by 

 intercalation with buff and greenish slates, especially on Exmoor. 



Fourthly. The Mortehoe slates are simply an unfossiliferous upper 

 portion of the Ilfracombe group ; the former being greenish and 

 glossy ; the latter grey, bluish, steel grey, and silvery, with local 



1 So far as I can understand, it would be difficult, if not impossible, to distinguish 

 between evergreen magnolias and those with deciduous leaves, in fossil remains. 



