274 Alfred Sherwood Romer 



Silurian includes " Bandes " Ecj, Ee^, and Ffi of Barrande, termed ea, efi and ey by 

 Kettner and Kodym (1919) and Boucek (1934). A certain amount of fish material 

 is present which, as Gross notes (1950, 64-65), is as yet insufficiently described. 

 Gross states that the beds containing fishes are " all of purely marine origin " and 

 hence counts all the Bohemian fish as part of his Silurian marine assemblage. A 

 closer examination of the actual sequence, however, suggests a somewhat different 

 interpretation. The stratigraphy has been most recently reviewed by Prantl and 

 Pribyl (1948, 67-73). Zones ea and e[3, which cover most of the extent of the Silurian^ 

 appear to be typically marine. There are no described fish except for one and possibly 

 tv^o spines of Onchus, with one of which some scales are associated; these are most 

 reasonably regarded, like the equally rare fragments in the English Ludlow and in the 

 Borszczow of Podolia, as strays from the adjacent land area. 



In ey, the " Lochkov Limestones " there is a diversified fish fauna, although speci- 

 mens are not abundant. Much of the Lochkov exposures show a typically marine 

 reef facies; the fish, however, occur instead in a shaly facies in which a series of 

 successive zones are present (Perner, 1918 a, 1918 b; Perner and Kodym, 1919, 1922; 

 Prantl and Pribyl, 1948, 73). This facies is stated to be limited chiefly to a seam in 

 the Radotin Valley between Prague and Kosor. The fish described by Perner occur 

 in the lowest zone. Perner and Kodym (1922, 67) state that in this zone " other 

 fossils are also rare "; since they give detailed faunal lists of invertebrates from all 

 other Silurian horizons but name no invertebrates from this zone, it would seem that 

 any non-vertebrate material present is inadequate to give evidence regarding ecological 

 conditions. Following the fish zone is a layer of black bituminous limestones with thin 

 intercalated shales, the lower part of which contains eurypterids and ceratiocarids 

 but no other fossils. Above this, the remainder — and greater part — of the shaly 

 facies contains typical marine invertebrate assemblages. 



We have, thus, in the lower zones of the shaly facies of the Lochkov the familiar 

 story of fishes, eurypterids and ceratiocarids with little or no indication of a marine 

 invertebrate fauna. Far from indicating a typical marine environment for the Lochkov 

 fishes, the evidence strongly suggests that their place of entombment was a near-shore 

 and possibly deltaic deposit.* 



5. Pas-de-Calais 



A second " island " region, independent of the advance of the main Downtonian 

 continental shore-line, is that of the Pas-de-Calais region of northern France. Here, 

 Leriche (1906) has described from the late Silurian or Downtonian of pit number 6 

 of the Lievin mining company of Pas-de-Calais two species of Heterostraci which 

 Gross appears to include in his marine list. The beds as a whole do contain good marine 

 fossils; but Leriche (18-21) gives the section in detail, as shown below. This definitely 



* Mr. Radvan Horny, of the Geological-Palaeontological Institute of the Charles University 

 and Dr. Ferdinand Prantl, Vice-Director of the Narodni Museum (Prague), in letters received 

 after completion of this paper, have furnished further information with regard to this situation. 

 They feel certain that these beds are all marine in nature, but that, on the other hand, the fragment- 

 ary and isolated condition of the fish remains indicates a necrocenosis, with post-mortem trans- 

 portation from another habitat — quite possibly, of course, fresh water. It is obvious that the Bohemian 

 fish faunas are of great interest, and it is to be hoped that our Czech colleagues will make a thorough 

 study of them 



