272 



THE GEOLOGIST. 



base of the Old Red ; and there is at least one Ichthyolite 

 common to both, and which does not occur in the superior 

 strata of the system in either country, the Dipterus macro- 

 lepidotus. The evidence may thus be summed up ; — We 

 learn from the geology of Caithness that this species of Dip- 

 terus was unquestionably contemporary with all the other 

 Ichthyolites described ; — we learn from the geology of Here- 

 fordshire that the shells were as unquestionably contempo- 

 rary with it. These two shells — are of a singularly mixed 

 character, regarded as a group uniting, says Mr. Murchison, 

 forms at one time deemed characteristic of the more modern 

 formations of the later secondary, and even tertiary periods, 

 with forms the most ancient, and which characterize the 

 molluscous remains of the transition rocks. Turbinated 

 shells and bivalves of well nigh the recent type may be found 

 lying side by side with chambered Orthoceratites and Tere- 

 bratula.'^ 



The vegetable remains of the formation are numerous but 

 obscure, consisting mostly of carbonaceous markings. 



We will again borrow rather largely from the pages of this 

 work, that we may the more clearly demonstrate the style in 

 which Mr. Miller treats many of the most important depart- 

 ments of the subject. In speaking of the distinctive cha- 

 racters of the various rocks, he says, to use his own words. 

 " Physiognomy is no idle or doubtful science in connection 

 with geology. The physiognomy of a country indicates al- 

 most invariably its geological character. There is scarce a 

 rock that does not affect its peculiar form of hill and valley ; 

 each has its style of landscape ; and as the vegetation of a 

 district depends often on the nature of the underlying depo- 

 sits, not only are the many outlines regulated by the mine- 

 ralogy of the formations which they define, but also in many 

 cases the manner in which these outlines are filled up. The 

 colouring of the landscape is well nigh as intimately con- 



