INFERIOR OOLITE. 
51 
Zone of Ammonites Parkinsoni. 
This zone is readily recognized by its fossils, which as a rule 
are plentiful from Dorsetshire to Gloucestershire. Away from 
Dorsetshire the characteristic Ammonite is not very abundant, 
but other fossils serve to distinguish it as far as the Cotteswold 
Hills and Oxfordshire. 
The zone has not been recognized in the midland counties nor 
in Lincolnshire, although it is quite possible that here and there 
portions of the Lincolnshire Limestone may be of the age. 
Mr. S. S. Buckman has suggested that this zone is capable of local 
subdivision into other zones, noting (in ascending order) the zones of 
A. Truellei, A. zigzag, and A.fuscus.* Such divisions cannot be regarded 
as of great stratigraphical value in this country, although the local 
succession of the Ammonites is interesting. 
List of Fossils from the Zone of Ammonites Parkinsoni. 
Ammonites fuscus. 
garantianus. 
Martins!. 
Parkinsoni (Fig. 26), 
polymorphus. 
subradiatus. 
Truellei. 
zigzag. 
Belemuites canaliculatus. 
Nautilus lineatus. 
Alaria hamus. 
Cerithium vetustum. 
Natica bajocensis. 
Nerinasa Guisei. 
Pleurotornaria fasciata. 
Purpurina bellona. 
inflata. 
Area Pratti. 
Astarte excavata (Fig. 20). 
Gryphaea sublobata. 
Lima gibbosa. 
pectiniformis. 
Myacites jurassi. 
Trichites undulatus. 
Trigonia duplicata. 
hemisphserica. 
signata. 
Rhynchonella spinosa (Fig. 29). 
Terebratula globata (Fig. 28). 
Phillipsi (Fig. 27). 
sphaeroidalis. 
Stephani. 
Waldheimia carinata. 
Clypeus altus. 
Ploti (Fig. 30). 
Collyrites ovalis. 
ringens. 
Holectypus depressus. 
hemisphsericus. 
(Corals and Sponges). 
Dr. Hinde observes that in this subdivision British Jurassic 
Sponges reach their greatest development. Thus on the Dorset- 
shire coast, at Burton Bradstock, there are layers of limestone 
" mainly composed of masses of sponges growing attached to 
each other, apparently still in their natural position. The greater 
number are evidently siliceous sponges, but though they retain 
their original forms fairly well, their canal structures are largely 
obliterated, and the silica of their spicular skeletons has been 
entirely replaced by carbonate of lime."t 
* Rep. Brit. Assoc. for 1891 (1892,) p. 655 ; Quart. Journ. Geol. Soc., vol. 
xlviii., p. 447. 
f British Jurassic Sponges (Pal. Soc.), Part III., p. 190. 
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