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Fossil Fishes of the Upper Old Red Sandstone. 
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EXPLANATION OF PLATES X. AND XI. 
Plate X. 
. Median dorsal plate of Coccosteuws magnus, Traquair; natural size. 
Kingsteps, Nairn. Original in the Edinburgh Museum. 
. Cosmacanthus Malcolmsoni, Agassiz; natural size, seen from the flat 
side. Scaat Craig near Elgin. Original in the Brickenden 
Collection, British Museum. 
. The same spine seen from the convex side. 
Plate XI. 
. Psammosteus tesselatus, Traquair; portion of a shield showing the 
external sculpture, and magnified two diameters. From King- 
steps, in the Edinburgh Museum. 
. External sculpture of the same; magnified eight diameters. 
. Psammosteus pustulatus, Traquair; fragment of a shield; natural 
size. From Scaat Craig, in the Brickenden Collection, British 
Museum. 
. External sculpture of the same; magnified. 
. External sculpture of Psammosteus Taylori, Traquair; magnified two 
diameters. From Newton Quarry, Alves, in the collection of 
Mr W. Taylor, Lhanbryde. 
. Scale of Holoptychius decoratus (Kichwald); magnified two diameters. 
¥rom Scaat Craig, in the Brickenden Collection, British Museum. 
. Tooth of Sauripterus crassidens, Traquair; natural size. From 
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Newton Quarry, in the Edinburgh Museum. 
