86 S. B. Woodivard' s Jurassic Rocks of Britain. 



tained to designate their subdivisions. A table of these is given, and 

 also one showing the principal subdivisions of the Jurassic rocks 

 from Dorsetshire to Lincolnshire. The sequence of the rocks, tbeir 

 changes, with their stratigraphical and palgeontological subdivisions, 

 their fauna and flora, and characteristic fossils are discussed. 



Mr. Horace Woodward then gives a general account of the Lias 

 formation and its organic remains, illustrated by numerous figures 

 of fossils. The opinions of Dr. Sorby and Mr. J. J. H. Teall on the 

 microscopic structure of the Lias are also quoted. A table is given 

 of the principal zones in the Liassic rocks with the names of the 

 Ammonites by which they are characterized. Attention is also 

 given to the origin of the limestones, many of which are considered 

 to be largely of sedimentary origin. 



Here, in the text, and also in the Catalogue of Liassic fossils at 

 the end of the Memoir (see pp. 330 to 378), they are given "under 

 the generic name Ammonites, because confusion must have arisen if 

 any attempt had been made to employ the subgeneric names. These 

 names, indeed, may be of service to the specialist who confines his 

 attention to the Ammonites, but they are of biological rather than 

 geological importance. Some of the names, indeed, have been changed 

 again and again since this Memoir was commenced, and many of the 

 species, unfortunately, are so split ujp that the multitude of names is 

 simply bewildering, and they become of little or no service to the 

 stratigraphical geologist. In some cases the same specific name has 

 been applied to mutations of diiferent subgenera of Ammonites ! a 

 course much to be deprecated, for it is likely that, if accepted as new 

 species, the names will eventually be replaced by others." 



The author then gives a general description of the Lower Lias, its 

 zones, organic remains, and characteristic fossils, with details of the 

 area over which it occurs, from the coast of Dorsetshire to the 

 Mendip Hills, together with sections along the coast and inland. 

 Other areas recorded are Harp tree and Chewton Mendip, Eadstock, 

 Jveynsham, Bath, Bristol, Westbury-on-Severn, Gloucester, Chelten- 

 ham and Tewkesbury. Thence we f)ass from Evesham to Stratford- 

 on-Avon, Banbury, Kugby, Market Harborough, Barrow-on-Soar, 

 the Vale of Belvoir, Lincoln, Frodingham, Shropshire and Cheshire, 

 and as far as Cumberland, these latter localities possessing " out- 

 liers " of the basement beds of the Lower Lias. 



The Middle Lias is treated in a similar manner with its zones of 

 Ammonites spinatus and margaritatus. Figures are also given of 

 various characteristic Middle Lias fossils, with a list of all the 

 organic remains. Then follow local details of the areas over which 

 the Middle Lias extends, in Dorset, Somerset, Gloucester, Oxford, 

 Northampton, Warwick, Leicester, Kutland, Lincoln, and Shropshire. 



The Upper Lias, with its zones and characteristic remains, is dealt 

 with as in the preceding divisions, including the topographical area 

 over which it extends. Many new facts are recorded, especially with 

 reference to the Lias of Lyme Eegis, to that of South Wales and of 

 Shropshire. The record of a new boring at Mickleton in Gloucester- 

 shire, affords evidence that there we have the greatest known thick- 

 ness of Lias in this country—no less than 1,360 feet. 



