Limestones of South Devon. 729 



cassidea, and Spirifera trapezoidalis, but the T. Wilsoni and S. trapezoidalis 

 are probably distinct from the Silurian shells. The corals are Favositespoh/- 

 morpha, F. spongites, F. Gothlandica, F. fibrosa, Porites piriformis, 

 Cyathophyllum turhinatum, C. ccespitosufu and Fenestella antiqua. The 

 Favosites polymorpha occurs abundantly in Devonshire, and it is not rare 

 in the upper Silurian formations; but the specimens which I have seen from 

 Plymouth and Newton Bushel resemble more nearly the variety figured by 

 Goldfuss from Paffrath than that found in the Ludlow rocks ; the Porites 

 piriformis is equally abundant in the limestones of Devonshire and Wenlock ; 

 but the remaining five species, as far as I am acquainted with the collections 

 of Mr. Hennah, Mr. Austen, and Mr. Sharpe, are not common. The more 

 abundant corals are those peculiar to the limestones. 



A vast amount of work remains to be done with respect to the Devonshire 

 organic remains ; but I rejoice to know that the task has been placed in the 

 hands of Mr. Phillips, who is not only well qualified but ready to overcome 

 every difficulty ; and it cannot be long before we are supplied with the fullest 

 and most satisfactory information. 



If it should be urged, that it was unjustifiable to assume from organic re- 

 mains alone, the age of the Devonshire limestones, it may be replied that at 

 that time no base line had been laid down, south of Dartmoor, from which an 

 order of superposition could be established. It may be also stated, that 

 organic remains had not long before j)roved faithful guides in a district 

 in which mineral character and order of superposition were inapplicable. 

 Through the exertions of Captain Smee, Colonel Pottinger, Colonel Sykes, 

 and Captain Grant, we had become aware of the existence of two series of 

 formations in Cutch and the Desert to the eastward ; and that one of them 

 could be placed in the parallel of the oolite series of England, because its 

 fossils were generically and in part specifically the same, and differed as a 

 whole generically and essentially from the fossils of any known transition or 

 tertiary district. In this instance we have an example of organic remains en- 

 abling the geologist to unite tracts separated by continents, — not, be it ob- 

 served, by establishing the identity of the fossils of subdivisions of formations, 

 but on the broad basis of the Fauna of a peculiar period in the history of our 

 globe. (See ante, pp. 289, 715.) 



Again, another instance may be quoted of the value of organic remains, it 

 rightly applied, in determining the relative geological age of a distant region, 

 and in the present case of one inaccessible to Europeans. The Ammonites 

 lately laid upon the Society's table by a near relative of the lamented Cap- 

 tain Alexander Gerard, and specimens of which have been long known, prove 



