Presidential Address to Geological Section. 465 



Climatius (C. ornatus, Ag.). The abundance of Gephalaspis (C. Gampbell- 

 tonejisis, Whit., C. Jexi, Traq.) and of Climatius spines is characteristic 

 of the Lower Devonian rocks of Canada. 



The Old Eed Sandstone of Lome has recently yielded organic remains, 

 akin to those found in Forfarshire, south of the Grampians, viz. 

 Cephalaspis Lornensis (Traq.), and two species of myriapods {Gampecaris 

 Forfar ensis and a species of Archidesnnis).^ 



In the deposits of Lake Orcadie, north of the Grampians, quite 

 a different fish fauna from that of Forfarshire appears. Dr. Traquair has 

 noted that there are no species common to the two areas, and only two 

 genera, viz. Mesacantkus and Gephalaspis. The latter genus is, however, 

 represented in Caithness only by a single specimen of a species 

 (0. magnifica, Traq.) different from any found elsewhere. It might here 

 be observed that Gephalaspis is represented also in the Upper Devonian 

 rocks of Canada by a single specimen of a peculiar species (C. laticeps, 

 Traq.), and hence Dr. Traquair has shown that, though Gephalaspis is 

 most abundant in the Lower Devonian, it extends also into the upper 

 division of that system. It further appears that Osteolepidte {Osteolepis, 

 Diplopterus), Rhizodontidaj {Tristichopterus, Oyroptychius), Holoptychiidae 

 (Gb/ptolepis), Asterolepidse {Pterichthjs, Microbrachius), CtenodontidcB 

 (Dipterus) are abundant in the Orcadian fauna, none of which has occurred 

 in the Lower Old Red Sandstone of Forfarshire, the West of England, or in 

 the Lower Devonian rocks of Canada. Dr. Traquair recognized, however, 

 the identity of the fishes from the well-known fish band in the basin of the 

 Moray Firth with those brought from the west part of Orkney, though 

 these forms did not quite agree with the fossils from the Thurso district. 

 He subsequently found that the fish fauna from the Orcadian beds in the 

 Moray Firth basin is represented in Caithness by that of Achanarras ; 

 and, further, that two other faunas occur in the Caithness area — that of 

 Thurso and that of John o' Groats, as given below : — 



T 1 , ^ , f Tristichopterus alatus, Egert. 



Johno Groats . . . [Microhrfchius I)icki,Tr^c^. 



( Coccosteus minor, H. Miller. 

 Thurso . . . . < Thursius pholidotus, Traq. 



( Osteolepis microlepidotus, Pander. 



( Pterichthys, three species. 

 Achanarras . . . . < Chcirolepis Trailli, Ag. 



( Osteolepis mac role pidotus, Ag. 



In 1898 appeared an important paper by Dr. Flett on "The Old Red 

 Sandstone of the Orkneys," ^ in which he described the results of his 

 detailed examination of the islands. He proved the existence there of 

 three fish faunas, and their correspondence with those identified in Caith- 

 ness by Dr. Traquair. From the evidence in the field he adopted the 

 following order of succession and correlation of the strata : — 



3. Eday Sandstones and John o' Groats beds. 



2. Rousay and Thurso beds. 



1. Stromness, Achanarras, and Cromarty beds. 



A further important result of Dr. Flett's researches in the Old Red 

 Sandstone of these northern isles was communicated to the Royal 

 Society of Edinburgh this year. He has found in the Shetland beds, 

 which had previously yielded no fossils save plants, fragments, identified 

 by Dr. Traquair as Holonema, a fish new to Britain, but occumng in the 

 Chemung group of North America, the subdi^^3ion of the Upper Devonian 

 that immediately underlies the Catskill red sandstones, with remains of 



' Summary of Progress Geol. Surv. 1897, p. 83. 

 2 Trans. Eoy. Soc. Edinb., vol. xxxix, p. 383. 



DECADE IV. — VOL. VIII. — NO. X. 30 



