52 Notes on Wiltshire Geology and Paleontology. 



extracted, and more than one company has been formed for utilizing 

 it for gas manufacture and for paraffine. Hitherto one difficulty is 

 insuperahle, arising from the fetid odour it emits when heated. 

 Ship-loads of it were sent to some London gas works, and to France, 

 the stench soon made itself perceptible in the neighbourhood of the 

 works, and the proprietors were compelled to cease using it and 

 would have been only too glad to have paid return freights to have 

 got rid of the material. Could this difficulty be overcome its 

 commercial value may be seen when it is stated that whilst New- 

 castle coal gives 8,000 feet of gas per ton, with an illuminating 

 power equal to twelve candles, Kimmeridge Shale gives 12,000 

 cubic feet of gas per ton, with an illuminating power of eighteen 

 candles. At Swindon these clays are used for brick-making. They 

 contain an abundance of organic remains, though of but few species 

 and those usually much crushed and distorted. The shells of the 

 Ammonites still retain all the nacreous colours of the rainbow. The 

 liassic period has usually been called the " age of reptiles,'' but if 

 the Kimmeridge Clays were as extensively worked they would vie 

 with it for this designation. Some of the genera living at the 

 period must have been formidable creatui'es. Not long since remains 

 of a new genus, named by Professor Owen, Omosavrus armatus were 

 found at Swindon. Great care was exercised in the removal of the 

 septarian-like stone in which they lay and in their after development. 

 It contained the pelvic portion of the animal with limb bones and 

 some of its vertebrae, and so far as it goes it is a grand specimen, the 

 femur alone is 3| feet in length. The lower jaw of another genus, 

 Pliosaums, was for a long time stowed away undeveloped at the 

 Swindon works, until stumbled upon by Mr. Cunnington. I have 

 found part of a jaw near Melksham, and the genus is found also at 

 Kimmeridge. A tooth of this creature has been found a foot long. 

 Bothriospondylus, Cetiosaurus, Ichthyosaurus, Plesiosaurus, Teleo- 

 sanrus, and Steneosaurus also occur in this formation. 



The Poitland and Purbeck beds, which overlie the Kimmeridge 

 Clay, are the upper members of the Oolitic series, and present a re- 

 markable contrast with the latter. The physical conditions under 

 which they were deposited must have been very different, for the 



