FOSSILS. 



577 



Scotland. The rocks in the West of England are apparently of later 

 deposition and of marine origin, while the " Old Red " is apparently a 

 fresh-water deposit. It is very " arenaceous," and owes its tint chiefly to 



Fig 657. Graptolites. 



iron, although there are circumstances in which it appears neither as a 

 sandstone nor with a red colour; but red sandstone describes the true forma- 

 tion very accurately. 



In this water-deposited system, whether in lakes or by the sea, we find 

 a considerable advance upon the Silurian. We have flora in more variety 

 seaweeds and ferns. The remains are all aquatic. We have nothing higher 

 in the scale of creation than the fish, the first vertebrates ; and judging by 



Fig. 658." Doulle-winged " Fish. 



varieties a very considerable time must have elapsed during which the Old 

 Red Sandstone was deposited. The dipterus or double- winged is 

 herewith shown as an example of the fossil fish of the Old Red Sandstone 

 period. 



It is curious that no remains of any land-inhabiting animals have been 

 discovered in this system whether in the Old Red or the Devonian 

 formations (the Lower and Upper Red Sandstones). We can only 

 distinguish the remains of aquatic animals or plants. We may picture the 

 great cuttle-fish, the nautilus, and the dipterus, with various orders of 



37 



