INTRODUCTION. ix 
Museum of Practical Geology, and the Museum of Science 
and Art, Edinburgh ; and, in 1861, the Rev. J. M. Joass, 
LL.D., of Golspie, discovered a new fish-bearing horizon 
at Edderton, near Tain, Ross-shire. Within the last few 
years, Mr. Jex, collector to Mr. Damon, of Weymouth, 
has made successful excavations in the well-known nodule 
beds of Lethen Bar (Nairn), Tynet Burn (Banff), and 
Gamrie (Banff), and thus greatly enriched the British 
Museum and the Museum of Science and Art, Edinburgh ; 
and the Worcester Museum owes a small but fine series of 
Thurso fossils to the generosity of Dr. Erlin Clarke. The 
Lower Old Red Sandstone of Forfarshire has been explored 
by Mr. James Powrie, F.G.S., of Reswallie, whose fine 
collection contains the types of several new genera and 
species described by himself and Professor Ray Lankester, 
F.R.S. ; the late Rev. Hugh Mitchell also obtained several 
specimens from the same beds; and Mr. Jex has more 
recently collected a fine series, now preserved in the British 
Museum and the Museum of Science and Art, Edinburgh. 
The Upper Old Red Sandstone of Elgin and Nairn 
yields many fragmentary remains of fossil fishes, and the 
early collections of Robertson, Malcolmson, and Patrick 
Duff, furnished several of the type specimens described 
by Agassiz. The Robertson Collection was dispersed by 
auction in London, about 1854, and some of the specimens 
were purchased by the British Museum, while others 
ultimately reached the Geological Society ; several of the 
types, however, are missing. The Malcolmson Collection 
forms a small series in the Forres Museum, and that of the 
late P. Duff is now for the most part incorporated with 
the collection of Mr. Powrie, a few specimens being also 
in the Geological Society's Museum. About forty years 
ago, Major Lambert Brickenden collected a fine series of 
Holoptychian and Asterolepid remains from Scat Craig, 
still preserved in his private cabinet ; and quite recently 
Dr. R. H. Traquair has secured for the Edinburgh Museum 
