706 PR RAMSAY H. TRAQUAIR ON THE DISTRIBUTION OF FOSSIL FISH-REMAINS 



It is also interesting to note that nine species given by Wellburn as occurring in 

 the Lower but not in the Middle Coal Measures of Yorkshire are found in the list from 

 the Middle Division in North Staffordshire. They are : — 



Pleuracanthus Wardi. Elonichthys caudalis. 

 Janassa linguceformis. „ oblongus. 



Acanthodes major. Bhadinichthys Planti. 



„ Wardi. „ macrodon. 



Sagenodus inequalis. 



We see, then, that Yorkshire corroborates the evidence of North Staffordshire, 

 Northumberland, and Scotland in this, that nearly all the common Upper Carboniferous 

 estuarine fishes being found in both the Lower and Middle Coal Measures, it is not 

 possible to divide these strata into ichthyological life-zones at least. For the establish- 

 ment of such zones must chiefly depend on the common and characteristic species, not 

 on those which are rare, or, it may be, met with only in one locality or bed. 



The fishes from the other English coal fields do not seem to have been so exhaustively 

 collected, but I have seen nothing from any of them contrary to the above conclusions, 

 namely, that in the Estuarine Fish-life of the Carboniferous System in Great Britain 

 there are only two great chronological divisions, Upper and Lower. That is to say, 

 keeping the true Upper Coal Measures out of view, for as yet, strange to say, we have 

 no fish-remains from that series. Those from the " Transition " series of Kidston are 

 ordinary Lower and Middle Coal Measure species ; but it is, of course, very probable 

 that, if we knew the fishes of the Upper Coal Measures, they might form a very 

 different assemblage. 



A word as to the Millstone Grit. " According to Mr Kidston, the plants of this 

 division are entirely Upper Carboniferous in aspect. — What of the fishes ? 



I have already stated that I have seen no determinable fish-remains from the 

 Millstone Grit series in Scotland, but Mr Wellburn has recorded a number from this 

 series in Yorkshire and Lancashire, which, according to his determinations, are partly 

 Lower Carboniferous marine species, partly Upper Carboniferous estuarine forms. # 

 Judging from the latter, the evidence of the plants is corroborated, but. the question 

 also occurs to our minds, namely — Did the marine fish-fauna of the Carboniferous 

 epoch change less rapidly than that of the estuaries and lagoons — or what was its 

 condition after the latter had undergone so extensive a change as came in at least with 

 the commencement of the Coal Measure period. We have as yet no answer to that 

 question so far as Great Britain is concerned, though the marine Upper Carboniferous 

 fish-remains of Miatschkowa, in Russia, are certainly different from those of the 

 Carboniferous Limestone of other parts of Europe. 



* Geological Magazine (4), vol. viii., 1901, pp. 216-222. In this paper Mr Wellburn enumerates nineteen forms, 

 of which four — Cladodus mirabilis, Pristodus falcatus, Pcecilodus Jonesii, Urodus elongatus — occur in the Lower Carbon- 

 iferous marine beds; three — Acanthodes Wardi, Stra2)sodus sulcatus, Elonichthys Aiikeni — are Upper Carboniferous 

 Estuarine species ; one — Acrolepis Hopkinsi — is common to both divisions of the system. Psephodus minutus and 

 Euctenodopsis te7iuis are described as new, but the remaining nine are not determined specifically. 



