so MONOGRAPH OF DURA DEN. 



where frog-like reptiles enjoyed the necessary conditions of an 

 amphibious life. 



The following is from an extensive and excellent Paper of 

 R. Godwin-Austen, Esq., on the coal-measures beneath the 

 south-eastern part of England, in the Quarterly Journal of the 

 Geological Society of London for February 1856 : — 



" Much confusion in the chronology of geological changes has been caused 

 by the reference of this formation to the marine series. If due weight be 

 allowed to the facts of an accompanying terrestrial and fluviatile vegetation, 

 to the occurrence of the genus Cyclas, together with air-breathing oviparous 

 quadrupeds and terrestrial Chelonians, the early suggestion of Dr. Fleming, 

 though based on other considerations, will surely be adopted ; and the Old 

 Eed Sandstone of Scotland will be referred to the lacustrine series of forma- 

 tions. The ' Old Red Sandstone' fishes offer a subject well worthy of special 

 treatment, with reference to the conditions of the area of water in which they 

 lived ; but the conclusions would probably be in accordance with those of 

 Dr. Mantel! ; that these conditions were such as those of the Lepidosteus and 

 Polypterus. 



" Of the three divisions into which Sir R. Murchison divided the ' Old 

 Eed Sandstone' series of the Welsh area, the lowest or ' Tilestone grjup,' 

 which alone contains the remains of marine forms, has been since very gene- 

 rally referred to the 'Upper Ludlow' deposits. The two higher divisions 

 alone represent the typical ' Old Red Sandstone ;' of these the argillo-calca- 

 reous or ' Cornstone' group contains just such an assemblage of fishes as is 

 met with in the palaeozoic fluvio-lacustrine deposits of Scotland ; whilst the 

 upper or ' conglomerate and sandstone group,' which as yet has only afforded 

 the remains of a Holoptychius, includes somewhat abundantly the spoil of a 

 terrestrial surface. On such considerations the ' Old Red Sandstone' of Here- 

 ford, Monmouth, and Somerset becomes the representative of another fresh- 

 water area, the relation and extent of which are indicated in the accompanying 

 Map (PI. I.) Had not the true character of these two peculiar assemblages 

 of depositions been misapprehended, the creation of a ' Devonian System ' 

 would not have been needed. 



" There are traces of ' Old Red Sandstone ' at intermediate places between 

 the two great areas of Wales and Scotland ; and these are of interest, as they 

 indicate with equal clearness an immediate subordination to a terrestrial sur- 

 face. The little patches which are dotted along the eastern skirts of the mass 

 of the old slate mountains of Westmoreland and Cumberland are in every case 

 so closely related to the rocks of the particular locality, as to suggest that they 

 are the alluvial beds of the ancient valley-courses of tliat region. A like local 

 relationship, as was long ago observed by M. Bone,* is to be traced along the 

 whole of the junction-line of the ' Old Red Sandstone of Scotland ;' and here 

 the accumulation often parts with its character of water-rounded conglomerate, 

 and assumes that of the angular talus so common in subaerial detritus." 



* Geul. dc VEciissc. 



