1 873-1 Present State of the Devonian Question. 107 



each other than fossils from different parts of the carboni- 

 ferous slate differed from each other ; that the fossils of 

 both groups warranted the conclusion that they might have 

 been geologically contemporaneous.* 



The palaeontological evidence cannot, therefore, be looked 

 upon as decisive. The Devonian beds contain some species 

 which are also found in silurian rocks, and many species 

 that occur in the mountain limestone. The old red sand- 

 stone does not contain any of these fossils; "there are no 

 marine forms in the old red sandstone."! Certain fish 

 remains have, however, been found by Mr. Pengelly^ in the 

 Devonian rocks of Cornwall, which are also found in the 

 old red sandstone. These include Pteraspis and Phyllolepis 

 concentricus. This, Mr. Jukes remarks, is the strongest pre- 

 sumptive evidence yet derived from fossils in favour of the 

 contemporaneity of the two formations. Nevertheless, he 

 adds, it is not conclusive proof, for it is obvious that the 

 occurrence in the Devonian rocks of species of fossil fish 

 belonging to the same genera as those of the old red sand- 

 stone no more proves the Devonian beds to have been con- 

 temporaneous with the old red sandstone, than the occur- 

 rence of species of trilobites, of the same genera as those in 

 the Silurian rocks, prove the Devonian rocks to be contem- 

 poraneous with the Silurian. § Therefore, we must agree 

 with Jukes that the geological age of the fossils must be 

 proved by the stratigraphical position of the beds. 



In setting forth the present state of the question, two 

 points connected with the subject, which have recently been 

 brought forward, may be referred to. 



An interesting feature has been noticed by Mr. T. M. Hall 

 in connection with the granites of Lundy Island, South 

 Devon, and Hestercombe, near Taunton (first described by 

 Mr. Leonard Horner||). He remarks that, although the 

 most remote of the three patches, " the so-called granite 

 (syenite) of this last locality has been regarded as possessing 

 a more intimate connection with Lundy Island, since the 

 general run of the Palaeozoic rocks in North Devon and the 

 adjoining portion of West Somerset is from east to west ; 

 and it might, therefore, be suggested that least resistance 

 would be afforded to the intrusion of an igneous rock 



* Jukes and Geikie, Manual of Geology, 1872, p. 763. 

 t Etheridge. op. cit., p. 679. 



+ Mr. Pengelly stated that he had found 300 specimens of Pterasridian 

 fishes in the Devonian rocks. Brit. Assoc. Meeting, Exeter, 1869. 

 § Jukes, Notes on Parts of South Devon and Cornwall, p. 42. 

 || Trans. Geol. Soc, vol. iii., p. 348. 



