﻿1851.] 



SALTER ON SILURIAN FISH REMAINS. 



265 



fully described and figured it in the 1st part of the " Catalogue of the 

 Woodwardian Museum," just published, it is unnecessary to speak 

 more of it here, except that I have examined it at Cambridge, and 

 quite agree with him in rejecting it from the class of Fishes. 



That the existence of fish in these early deposits has gained general 

 credence, is evidenced not alone by the work of Mr. Miller, cited 

 above. Alcide D'Orbigny, in his ' Cours Elementaire de Paleontologie/ 

 published in 1849, refers to one species of the Cestracionidce in 

 the etage Silurien, which in his scheme includes only the Lower 

 Silurian rocks of English geologists ; and in his table of the distribution 

 of families, the Cestracionidce make their first appearance in the 

 Silurien inferiear, and continue, although in smaller numbers, 

 through the etage Murchisonien, or Upper Silurian. He has since 

 repeated this table in the ' Annales des Sciences' for 1850. 



As Mr. Miller's work also gives currency to the idea long held by 

 Prof. Sedgwick, as well as by other geologists and myself, viz. that 

 the Bala limestones lie below the rocks of Plynlimmon, and these 

 again beneath the Llandeilo flags of South Wales, it may be well here 

 to refer to the paper by Prof. Ramsay, in vol. iv. of the Quarterly 

 Journal, p. 294, in which, as the result of the observations of the 

 Survey, the contemporaneity of all these beds is directly stated or 

 implied. Although the Bala limestone itself cannot be traced into 

 South Wales, there is a peculiar and very constant band of sandstone 

 and conglomerate, occurring at several hundred feet above it, which 

 extends down continuously into Radnorshire, occupies many tracts in 

 the country about Plynlimmon and the central parts of Wales, and 

 appears in great force in Caermarthenshire, at about the same eleva- 

 tion above the Llandeilo limestone as it does at Bala. So that, if not 

 exactly the same calcareous bed (and the perfect identity of their 

 fossil contents would lead us to believe they are the same), these two 

 bands of limestone lie on the same geological horizon, and in like 

 manner the rocks of Central Wales are proved to be of equal age, 

 although destitute of the calcareous beds, and almost void of fossils. 



We may now, therefore, safely say, that in the great Lower Silurian 

 series there has been no evidence published which justifies us in 

 assigning so early a date to the class of Fishes. 



As yet no remains of this order have been quoted from the Caradoc 

 Sandstone, for the scales of a fish, described by Prof. M'Coy in 1846 

 as from the " Caradoc Sandstone" of Wexford, belong to the Llandeilo 

 flags, and to nearly the parallel of the Llandeilo and Bala limestones. 

 And his opinion, expressed in a letter to me, is at present that these 

 so-called scales are plates of a peculiar Cystidean. In this view I per- 

 fectly agree ; they are very like some species of this tribe which occur 

 plentifully in South Wales, and he had himself, when describing the 

 fossil*, noticed their striking analogy with these plates, although 

 there were still some peculiarities which induced him to refer them 

 provisionally to Fish. 



* Synopsis of the Silurian Fossils of Ireland, published under the auspices of 

 R. Griffith, Esq., of Dublin. 



