456 



THE GEOLOGIST. 



some distance on its surface, apparently making the transverse tracks by- 

 means of its tarsi." A figure of this insect-track would have been very 

 acceptable in connection with the subject treated of in my above-mentioned 

 paper, loc. cit. p. 132, etc. 



T. EuPEET Jones. 



Royal Military College, Sandhurst. 



BEITISH ASSOCIATION MEETING AT CAMBEIDGE. 



THE CORELATIOlSr OF THE SLATES AND LIMESTONES OF 

 DEVON AND CORNWALL WITH THE OLD EED SANDSTONES 

 OF SCOTLAND. 



By W. Pengellt, F.a.S. 



The distinguished author of ' Siluria,' as geologists well know, has made 

 a tripartite division of the slates and limestones of Devon and Cornwall, 

 as well as of the Old Red Sandstones of Scotland, South Wales, etc., 

 and given chronological equivalency to the upper, middle, and lower 

 groups of each respectively. Thus he places the Barnstaple and Pether- 

 win beds — the latter being characterized by the presence of Clymenia 

 and Cypridina — on the horizon of the Upper Old E,ed, with its itolopty- 

 chius and PhyUolej^is ; the limestones of Torquay, Newton, and Plymouth, 

 in which are round String ocephalus, Calceola, Bronteus, Acervularia, etc., 

 are made to synchronize with the deposits of Caithness, etc., containing 

 the remains of Asterolepis, Coccosteus, etc. ; whilst the slates of Meadfoot, 

 etc., in South Devon, and Looe, etc., in Cornwall, distinguished by the re- 

 markable Coral Pleurodietyum prohlematicum, are regarded as the equiva- 

 lents in time of the Lower Old Eed rocks of Forfar and the North-east 

 Highlands, which are charged with Cephalasjpis, Pteraspis, and OncJius.^ 



Though this co-ordination may be said to have met a large acceptance, 

 it is not in keeping with the opinions of some who laboured long and sedu- 

 lously amongst the older rocks of Devon and Cornwall, nor is it un- 

 challenged by some existing writers. The late Sir Henry Dela Beche re- 

 garded "the bulk of the Devonshire and Cornish rocks as, at least in 

 XDart, equivalent to the lower beds of the Carboniferous Limestone, to the 

 passage beds between the Old Eed Sandstone and Carboniferous Lime- 

 stone of Ireland, South Wales, etc., and also to some portion of the 

 higher part of the Old Eed Sandstones of Herefordshire and adjacent 

 districts. "t The Eev. David Williams considered " the Devonian system 

 as occupying an enormous interval between the Old Eed Sandstone and 

 Mountain Limestone. Mr. Page says, " We shall use the term ' Devo- 

 nian ' as applying more particularly to the strata as developed in the 

 south of England, and the term ' Old Eed Sandstone ' as more especially 

 applicable to those of Scotland; believing, as we do, that the Caithness 

 and Forfarshire beds are on a lower horizon than the Enghsh Devonians, 

 and that it requires both developments to constitute the * system ' as at 

 present understood by European and American geologists. "§ Mr. Bete 

 Jukes says, " It is quite possible that the slates and limestones of Devon, 



* ' Siluria,' Srd edit., p. 433. 



t Memoirs Gool. Survey, vol. . p. 103. 



X Report Royal Gcol. See. of Cornwall, 1843, p. 123. 



§ ' Advauced Text-Book of Geology,' p. 123. 



