292 
INFERIOR OOLITE AMMONITES. 
The geological position op the SoNNiNiNiE ranges from the Goncavuin- to 
the Humphriesianum-zone inclusive. Since the early portions of this Monograph 
were written it has become necessary to modify somewhat the zonal nomenclature 
of the strata. The term Soiverhyi-zone was at first used in a wide sense to 
include all the strata which it was presumed lay above the Mmxhisonse-zone and 
below the Sauzei-zone (marl with green grains, Oborne). This view was 
supported by certain Ammonites from a disused quarry at Sherborne — species 
described by Waagen ; and these Ammonites apparently occupied an horizon 
above the Murchisonse-zone. Later on it became evident that part of the so-called 
" Soiverhyi-zone" ought to be definitely separated as Goncavum-heds or zone ; and 
I fully explained the matter (pp. 63 — 65). I suggested that the true " Sowerbyi- 
zone " of the Continental authors would probably be found between our Goncavum- 
and Sauzei-zones ; but as there was some obscurity I dropped the term Sowerhyi- 
zone, and used the term " Sauzei-zone " in a wide sense (see foot-note 4, 
p. 63). Recently the splendid collection of fossils made by Mr. Darell Stephens, 
F.G.S., came into my hands ; and it contained a magnificent suite of Ammonites 
from the disused Sherborne quarry. Their matrix shows that they came from the 
same bed, indicating that there evidently is a particular horizon characterised 
by a particular fauna ; and this fauna is certainly distinct from that of the 
(J oncavum- zone, or from that of the Sauzei-zone, so far at least as the "marl- 
bed with green grains" of Oborne, is concerned. 
This horizon, I take it, is the " Soiverhyi-zone " of the Continental authors ; but 
as there is still some uncertainty concerning its connection with the Goncavum- 
zone below, or how it is separated from the Sauzei-zone above, I cannot define 
these zones with precision. I hope to undertake investigations to clear this 
matter up. 
Upon our present knowledge, however, the strata in which the Sonnininss 
occur will be provisionally divided into four horizons : 
The lowest, the Goncavum-zone, a well-marked horizon over a considerable 
area of Dorset and Somerset. 
The second, the Sotuerhyi-zone in its restricted sense. Only the Ammonites 
from Sherborne exhibiting a certain matrix will be referred to this zone, except 
when additional evidence may be furnished by other localities. 
Thirdly, Sauzei-zone. The "marl-bed with green grains" of Frogden Quarry, 
Oborne, will be especially designated thus. Certain strata at Dundry,^ dominated 
by the genus Witchellia, are considered as belonging here. 
1 The following abridgment of a section at Duniiry, a celebrated locality for Sonnininx, may 
be useful : F^- I°- 
1. Limestone ... . . . . .60 
2. Marl . . . . . . . .09 
3. Soft whitish stone . . . . . . -i 0 
