232 LOWER OOLITIC ROCKS OF ENGLAND : 
echinata, Gervillia acuta, Nucula Menkei, Ostrea acuminata, 
O. Sowcrbyi, and O. subrugnlosa, represent the Bathonian 
side, while the species of Homomya, Modiola, Myacites, are more 
allied to the Bajocian. 
The Brachiopoda are about equally divided. Tcrebraiula 
(flobata passes upwards from the Inferior Oolite, while 
Waldheimia ornithocephala, aud its ally W, lagenalis, are Great 
Oolite forms. 
The Echinodermata, Corals, &c. are rare, and the Ostracoda, of 
which Prof. Jones and Mr. Sherborn have recognized 62 species, 
am; with three exceptions new. 
These observations after all serve to confirm those of Mr. 
Evheridge. who states that of 110 species from the Fuller's Earth, 
65 wore derived from the Inferior Oolite and 88 occur in the 
Great Oolite series.* 
Although numerical estimates of species cannot be said to 
furnish the most reliable data for classifying strata, yet the 
palseontological evidence favours our grouping of the Fullonian 
Beds with the Great Oolite. Again in lithological characters 
and method of formation, the Fullonian clays, marls, and earthy 
limestones, closely resemble beds in the Great Oolite of the 
counties of Gloucester, Oxford, and Northampton. The Fullonian 
formation, as Mr. Etheridge admits, is of a transitional character, 
but it is a subordinate and local accumulation, and, for general 
purposes of classification and correlation, not important enough to 
stand alone. It has been suggested that a divisional-plane be 
taken on top of the Lower Fuller's Earth Clayf ; but no such 
division is practicable, and to attempt it would be to violate the 
principles of stratigraphy. 
When we enter the region of east Gloucestershire and north 
Oxfordshire, it is difficult in places to separate the uppermost 
strata of the Inferior Oolite from the Fullonian Beds, for there 
are limestone-beds that may in point of time represent the lower 
clays of the " Fuller's Earth " of other tracts. Reference has 
already been made to these passage-beds. (See p. 129.) 
In the region south of Gloucestershire, however, the field- 
geologist has as a rule no difficulty in fixing the plane of division 
between " Fuller's Earth " and Inferior Oolite, for there is no 
marked alternation of limestones and clays at the junction ; and 
although we may occasionally find a band of limestone near the 
base of the Fuiionian, yet in places the surface of the Inferior 
Oolite is bored by Annelides and Lithodomi and the junction is 
well marked. 
We may therefore regard the Fullonian formation as extending 
from the Dorsetshire coast through Somersetshire and Gloucester- 
shire to the neighbourhood of Chipping Norton in Oxfordshire. 
In this northern area the upper Fullonian clays merge into the 
Stonesfield Slate Series ; and further on, both are to a certain 
* Stratigraphical Geology and Palaeontology, p. 422. 
f H. S. Solly and J. F. Walker, Proc. Dorset Nat. Hist. Club, vol. xi. p. 120. 
