GAVEY — LOWER LIAS, GLOUCESTERSHIRE. 33 



Underneath this bed, and at 14 feet below the surface, there is a 

 thin bed of ironstone, of a dark brown colour and of a rough uneven 

 fracture, differing from any hitherto met with ; it forms a continuous 

 layer of rounded and irregular nodular masses for about 400 feet, and 

 is from 6 to 8 inches thick. Some rare fossils were found in it, viz. 

 Lingula Beanii, Orbicula, large spines of a Cidaris, and a few other 

 fossils. 



The shale underneath this ironstone-bed becomes of a darker colour 

 and considerably harder and heavier the deeper the excavation is pro- 

 ceeded with. 



It is seldom that these beds are laid open to such an extent and 

 depth as shown in the section, PI. I. fig. 1. Their inclination, as 

 at the other end of the Tunnel, is towards the north at an angle of 

 one degree*. From the immense number of Cephalopods (chiefly 

 Ammonites 'planicostatus and Belemnites ovalis) which have been 

 found in this cutting, the shales appear to have been deposited in 

 deep water. They are more arenaceous in some parts of this cutting 

 than in others, forming thin slabs of a fine bluish sandstone, on which 

 many of the Echinodermata were found. There were also large slabs 

 of ironstone, of the same description as those found in the Tunnel, 

 but much more fossiliferous, many of them being almost entirely 

 composed of shells, &c. These slabs of ironstone were very nume- 

 rous, and many of them J 6 inches thick. Their upper and under 

 surfaces in many instances were covered with innumerable fragments 

 oi Pentacrini, together with many fine specimens of Starfishf . 



The Uraster GaveyiX, E. Forbes, was discovered lying on the upper 

 surface of a slab of sandstone, 12 inches thick, at 25 feet below the 

 surface, associated with fragments of Pentacrinites, Ammonites, and 

 other fossils. 



All the specimens of Tropidaster pectinatus^ and Cidaris Edwardsii 

 were found attached to the under side of a thick slab of ironstone at 

 about 20 feet below the surface. Almost all the specimens show 

 the ventral surface, and most of them had the spines attached to the 

 spiniferous plates ; the Cidaris, when first found, was entirely covered 

 with spines, so much so as to conceal the inter ambulacral plates. 



The Oyster-beds were very interesting, for I found them in situ at 

 different depths ; they were limited in extent, and the shells were 

 generally in a crushed state and varied in size from ^ an inch to 3-|- 

 inches in diameter. There were traces of Plants, and large frag- 

 ments of carbonized wood. One piece was about 7 feet long, and 

 more than 1 foot wide, but, being in a crushed state, it was only 1^ 

 inch thick ; it was converted into jet. Other pieces were of a dark 

 brown colour, impregnated with iron-pyrites. 



* The beds of shale were generally undisturbed throughout the cutting; but I 

 remarked that in one part, for the distance of forty yards, they were much dis- 

 torted, and had a waved appearance ; the ironstone was here lying in various 

 positions and the fossils were ground to pieces. 



t A new species of Ophioderma was found on one of them. 



X Mem. Geological Survey, Decade III. plate 2. 



§ Mem. Geological Survey, Decade III. plate 3. 

 VOL. IX. — PART I. D 



