5 
thus to afford convenient data by which to classify the succession 
of beds. In the “Middle Lias” these zones are distinguished 
by the following Ammonites in descending order :—The 1st or 
uppermost zone is that of “A. spinatus ”; the 2nd that of 
“A. margaritatus” ; 8rd “A. Henley” or “ capricornus ” ; Ath 
<A. ibe”; 5th “A. Jameson”; and lastly that of “A. armatus,” 
which rests conformably on the upper beds of the Lower Lias. 
Dr. Surruz showed how the “ Middle Lias” which appears but 
weakly below Bath, is traceable along the western slope of the 
Cotteswolds throughout Gloucestershire, and finds its greatest 
development in the neighbourhood where the party were then 
assembled. 
The rock here proved very fossiliferous, especially on the 
edges of the fissures, where the fossils were weathered out, and 
presented to the hammers and chisels of the geologists quite a 
museum of beautiful forms of life. ‘‘Ammonites spinatus” was 
abundant, and thus fixed the -horizon as that which is specially 
characterised by the presence of that Ammonite. But Dr. 
Smrrne, when he visited the quarry in company with Mr. Lucy, 
in the year 1878, had found “A margaritatus” (which distin- 
guishes the zone below) on the same horizon, or even somewha* 
higher in the quarry than the beds then under review. This 
produced a lively discussion between those who believe that 
these horizons do to a certain extent overlap one another, and 
those who maintain that nature produced these particular 
organisms as special creations which appeared at a certain point 
in time and became extinct at a certain other point, when they 
were succeeded by entirely distinct forms. Dr. Swrae further 
stated that on the occasion of his visit to the quarry with Mr. 
Lucy they were so fortunate as to acquire from a quarryman a ~ 
number of reptilian bones, which proved to be those of an 
Ichthyosaurus of an undetermined species, but probably belong- 
ing to “J. acutirostris” of Owen. These have since been 
deposited in the Museum at Gloucester. 
Attention was next drawn to a clay deposit of a peculiar 
character, which in a finely divided state had insinuated itself 
into fissures of the rock to a depth of 15 feet from the surface, 
