A SUMMER RAMBLE AMONG THE HEBRIDES. 181 



we set out to explore a bluff-headed parallelogramical pro- 

 montory, bounded by Thurso Bay on the one hand, and Murkle 

 Bay on the other, and which presents to the open sea, in the 

 space that stretches between, an undulating line of iron-bound 

 coast, exposed to the roll of the northern ocean. "We pass two 

 stations in which the hard Caithness flagstones so well known 

 in commerce are jointed by saws wrought by machinery. As 

 is common in the Old Bed Sandstone, in which scarce any 

 stratum solid enough to be of value to the workmen, whether 

 for building or paving, contains good specimens, we find but 

 little to detain us in the dark coherent beds from which the 

 flags are quarried. Here and there a few glittering scales 

 occur here and there a few coprolitic patches ; here and 

 there the faint impression of a fucoid ; but no organism suffi- 

 ciently entire to be transferred to the bag. As we proceed 

 outwards, however, and the fitful breeze comes laden with the 

 keen freshness of the open sea, we find among the hard dark 

 strata in the immediate neighbourhood of Thurso Castle, a 

 paler-coloured bed of fine-grainedsemicalcareous stone, charged 

 with remains in a state of coherency and keeping better fit- 

 ted to repay the labour of the specimen-collector. The in- 

 closing matrix is comparatively soft : when employed in the 

 neighbouring fences as a building stone, we see it resolved by 

 the skyey influences into well-nigh its original mud ; whereas 

 the organisms which it contains are composed of a hard, scarce 

 destructible substance, bone steeped in bitumen ; and the 

 enamel on their outer surfaces is still as glossy and bright as 

 the japan on a papier-mache tray fresh from the hands of the 

 workman. Their deep black, too, contrasts strongly with the 

 pale hue of the stone. They consist chiefly of scales, spines, 

 dermal plates, snouts, skull-caps, and vegetable impressions. 

 A little farther on, in a thick bed interposed between two 

 faults, the same kind of remains occur in the same abundance, 

 largely mingled with scales and teeth of Holoptychius, tuber- 



