FISHES OF THE OLD RED SANDSTONE. 



601 



Mr. G. Gordon believes, that from their position, the beds with ichthyolites are probably of the same 

 age as those of Clashbirmie in Perthshire, and of Strath Eden and Drum Dryan in Fifeshire. 



I owe this information to Mr. J. Malcolmson, F.G.S., who having recently brought away speci- 

 mens from the district, has obligingly enabled me to figure the conical tooth, and other portions 

 of fishes found in the same quarries, figs. 5, 6, f. 



I may here remark, that although I have never yet found a perfect specimen of Holoptychus 

 in the Old Red Sandstone of England, I have now no doubt, that the large "scale which I detected in 

 the Old Red Conglomerate near Crickhowell (p. 175) is identical with the scales which occur in 

 Perthshire, Murrayshire and Caithness. (PI. 2 bis. f. 3.) 



M. Agassiz must determine the genera and species to which the other remains of fishes found 

 near Elgin may belong. (Figs. 5, 6 and 7 ? are drawn from specimens belonging to Mr. Malcolmson.) 



The great thickness of the bony matter which supports the scaly covering (figs. 5 and 6.) is very 

 remarkable. It was this structure, so apparent in some of the Caithness fossils, which led Pro- 

 fessor Sedgwick and myself to refer them to the class of reptiles. Geoh Trans, vol. iii. p. 144. 



Diplopterus, Agass. 



The remarkable ichthyolite, which enabled M. Agassiz to establish the genus Diplopterus, was 

 found by Dr. Traill in Pomona, Orkney, the sandstones and schists of which were previously 

 •shown to belong to the Old Red System. — Sedgwick and Murchison, Geol. Trans, vol. iii. p. 141. 



M. Agassiz has not yet fully described this genus, though he tells us that it is of " the family 

 of Sauroid Jishes. Like the genus Dipterus, it has two dorsal opposite two anal fins, but the caudal 

 fin is of a very peculiar form; the throat is very large, and the jaws are armed with large conical 

 teeth." Recherches, vol. ii. p. 113. 



Osteolepis. 



This generic name was given to fossil fishes of Caithness (collected by Professor Sedgwick and 

 myself) by M. Valenciennes and Mr. Pentland; Geol. Trans, vol. iii. p. 143. The genus has since 

 been found in the Orkney Isles by Dr. Traill, and M. Agassiz has continued to use the name first 

 assigned to it. Two species occur in Caithness and the Orkney Islands (Osteolepis macrolepidotus 

 and O. microlepidotus), while a third, O. arenaceus, Agass., is found at Gamrie. As this genus 

 has not yet been found in the Old Red Sandstone of England, I refer my readers to the work of 

 M. Agassiz for the description of the Scottish species. 



The reader may perceive that there are yet two genera of Ichthyolites enumerated in the pre- 

 ceding table, the Cheir acanthus and Cheirolepis, Agass., to which I have not adverted, Through 

 the researches of Dr. Traill, who found the Cheirolepis Traillii and Cheiracanthus minor, Agass., 

 in Pomona, Orkney, there is no doubt that these genera belong to the Old Red System. 



Other species of these genera have been found at Gamrie, Banffshire, in which locality they were 

 first mentioned by myself, though I never examined the relations of the strata. Those relations 

 have since been described by Mr. Prestwich, in an able memoir on the coast of Banffshire, and ac- 

 cording to him, the nodules containing the Ichthyolites are imbedded in an argillaceous, horizontally 



