698 DR RAMSAY H. TRAQUAIR ON THE DISTRIBUTION OF FOSSIL FISH-REMAINS 



which are hardly within our control ; indeed, they come largely under the operation of 

 what we are pleased to designate as " chance." The foregoing lists cannot in any way 

 be considered as containing a complete record of the fishes contained in the Carboniferous 

 rocks of the district around Edinburgh. Nevertheless, it will be well, after having 

 worked at these remains for nearly thirty years now, to put together the general results 

 as to their distribution to which we are in the meantime conducted. These results are, 

 in the main, already known to those who are specially interested in palaeozoic ichthyology, 

 but a more concise account as to how the matter stands at present may not be 

 unwelcome to geologists in general. 



Lower Carboniferous. 



We have seen that the fish-remains found in the limestones of open sea origin at 

 Mayfield, Charlestown, and other places are different from those occurring in the 

 estuarine beds, and that they belong, in fact, to the marine fish-fauna characteristic of 

 the Mountain Limestone of England and Ireland. This fauna consists mainly of 

 Elasmobranch forms, Dipnoi and " Ganoids " being rare ; while, on the other hand, the 

 estuarine strata throughout the whole Carboniferous formation are characterised not 

 only by fishes coming under the two latter designations, but also by a set of Elasmo- 

 branchs which differ specifically and for the most part also generically from those of the 

 marine limestones. 



Earely do we find any commingling of these two faunae ; one notable exception being 

 at East Kilbride, in Lanarkshire, where the shale overlying the Calderwood Cement 

 Limestone contains such estuarine forms as Rhizodus Hibberti, Strepsodvs striatulus, 

 Elonichthys Robisoni, and Rhadinichthys ornatissimus, along with such typically 

 marine species as Petalodus acuminatus, Psephodus magnus, Pcecilodus Jonesii, 

 Psammodus porosus, etc. 



As to the zonal question, I am not aware that any definite succession of forms can 

 be established, either in Great Britain or in Ireland, on the fish-fauna of the marine 

 limestones. 



What, then, of the estuarine fishes in which the Lower Carboniferous rocks of the 

 Edinburgh district are so rich ? 



Our observations must commence with the Craigleith and Wardie beds, as no 

 specifically determinable fish-remains are available from the underlying strata ; but 

 from that horizon upwards this estuarine fish-fauna persists in its main features into the 

 Upper Limestone Group, the South Parrot Coal shale being the highest bed in the 

 Lower Carboniferous division from which fossil fishes have been in this region obtained. 

 And an examination of the accompanying table of vertical distribution shows that it is 

 scarcely possible to mark out satisfactory zones by means of the fishes, so far as the 

 Lower Carboniferous rocks are concerned ; — of the Upper we ishall presently speak. 



