136 PROCEEDINGS OP THE GEOLOGICAL SOCIETY. [May 18, 



also described at p. 208 of ' The Sketch-book of Popular Geology/ 

 it is needless to introduce it here. Peeling confident that no apology 

 is due for submitting to the Geological Society the foregoing pas- 

 sages from the pen of one of the most original and philosophical 

 writers of the age, I will close the series with a paragraph highly 

 characteristic of the resolute yet patient method of his scientific 

 labours : — 



" For my own part, I am determined to go stubbornly on, adding 

 fact to fact, and testing earlier by later observations, convinced 

 that, if I succeed in getting Truth out of the deep well in which, in 

 this game of Ichthyolitic reading, as in so many others, it is her 

 nature to hide herself, her identity will be ultimately recognized, 

 however authoritatively it may be challenged or denied on her first 

 appearance." 



2. On the Yellow Sandstone of Dura Den and its Fossil Fishes. 

 By the Bev. John Anderson, D.D., F.G.S., &c. 



[This Paper was withdrawn by the Author with the permission of the Council.] 



(Abstract.) 



In his geological remarks on Dura Den, the author described the 

 sedimentary strata in the vicinity as consisting of (in ascending- 

 order) — 1. Grey sandstone, the equivalent of the Carmylie and 

 Forfarshire flagstones, with Oephalaspis and Pterygotus. 2. The 

 red and mottled beds, such as those of the Carse of Gowrie, and the 

 Clashbennie zone with Holoptychius nobilissimus, Phyllolepis concen- 

 tricus, and Glyptolepis elegans. 3. Conglomerates, marls, and corn- 

 stone, with few and obscure fossils. 4. The Yellow Sandstone, rich 

 in remains of Holoptychius and other fishes, and about 300 or 400 

 feet in thickness. This sandstone is seen to rest unconformably on 

 the Clashbennie series of the Old Bed at the northern opening of the 

 Den, and at the southern end is unconformably overlain by the Car- 

 boniferous rocks. It is also exposed beneath the lower coal-series 

 of Cults, the Lomonds, Binnarty, and the Cleish Hills. It is seen 

 also in Western Scotland (Benfrewshire and Ayrshire), and in Ber- 

 wickshire and elsewhere in the south, with its Pterichthyan and 

 Holoptychian fossils. In the author's opinion it is entirely distinct 

 from the " Yellow Sandstone " of the Irish geologists. 



At Dura Den one thin bed in the Yellow Sandstone especially 

 teems with fossil fish. The Pamphractus-bed, towards the top of 

 this thick deposit, is the only other stratum bearing fossil remains. 



In 1858 a remarkably fine Holoptychius Andersoni was met with 

 in the fish-bed ; and this, with many other specimens, fully bears 

 out Agassiz's conjectures for completing the form and details of the 

 fish where his materials had been insufficient. Dr. Anderson thinks 

 that the supine position of the Holoptychii is of rare occurrence ; he 

 has observed them usually to lie on their side. H. Andersoni and 

 H. Flemingii are regarded by the author as specifically one, as he 



