154 Proceedings of the Royal Physical Society. 



coveries in the Old Eed Sandstone of John o'Groats, as well 

 as of several beautiful little Acanthodian fishes, two from 

 Caithness, also discovered by Mr Peach, and others from the 

 grey beds of Forfarshire, brought to light by several indus- 

 trious Forfarshire collectors, among whom were the Eev. 

 Hugh Mitchell, the Eev. Henry Brewster, Mr Walter M'Nicol, 

 and Mr Powrie of Eeswallie, of whom more anon. To Scot- 

 tish carboniferous ichthyology Sir Philip Grey-Egerton also 

 contributed descriptions of two new selachian species, Gtena- 

 canthus hyhodoides and C. nodosus ; and his paper on the pro- 

 bable identity of Agassiz's genera, Pleuracanthus and Di;p- 

 lodus, is also of equal importance to the investigator of the 

 fossil contents of the Scottish as of the English coal mea- 

 sures. 



A third great era in the history of palaeozoic ichthyology 

 may be said to have commenced with the publication of the 

 researches of the distinguished Eussian naturalist, Dr Chris- 

 tian Heinrich Pander. With his first great work, the 

 " Monographic der Fossilen Fische des Silurischen Systems 

 des Eussisch-baltischen Gouvernements," published in 1856, 

 we have here nothing to do, save to remark that if the singular 

 little tooth-like bodies, known as " conodonts," be in reality 

 what many at the present day suppose them to be, namely, 

 the teeth of Myxinoid fishes, then we shall have abundant 

 evidence of the prevalence of these lowly organised fishes far 

 back in Lower Silurian times. It is his three subsequent 

 publications, on the " Placodermi," on the " Ctenodipterini," 

 and on the " Saurodipterini, etc.," appearing respectively in 

 1857, 1858, and 1860, which attract our attention, dealing as 

 they do with the fishes of the Old Eed Sandstone, and very 

 largely with Scottish specimens. Fish remains are of fre- 

 quent occurrence in the Old Eed Sandstone of Eussia ; many 

 had been previously described by Eichwald as far back as 

 1839, as well as by Agassiz in his Monograph of the fishes 

 of the Old Eed Sandstone. These remains are, however, 

 mostly very fragmentary; to read them aright, comparison 

 with more entire fishes was necessary, and this want was 

 supplied by the liberality and enthusiasm of a member of 

 the Eussian Academy, Herr von Hamel, who undertook a 



