INFERIOR OOLITE. 45 
The Inferior Oolite above the stages previously described 
(p. 39), was divided by Oppel into the four zones, which, in 
ascending order, comprise those of A. Murchisonce, A. Sauzei, 
A. humphriesianus, and A. Parkinsoni. 
In this country we find it generally sufficient to adopt a broad 
grouping of the beds into the zones of A. Murchisoncs and A. 
Parkinson?', because other zones are difficult to distinguish except 
locally ; and where the distinctive species of Ammonites are 
absent, it is by no means easy to say to what extent the minor 
zones are represented, as other forms of Mollusca are somewhat 
variously distributed. For convenience of description I shall 
follow the general grouping of Mr. Hudleston, and refer to the 
fossils of the Inferior Oolite under the following principal 
zones : 
TT T\- [A. Parkmsom. 
U nper Division { A , , . . 
[_A. humphrzesianus. 
A. Murchisonce. 
A. opalinus. (See p. 39.) 
v_ 
Lower Division-^ 
INFERIOR OOLITE. (LOWER DIVISION.) 
Zone of Ammonites Murchisonce. 
The zone of Ammonites Murchisonce is, as a rule, well-marked, 
although the Ammonites, so abundant in Dorsetshire, are com- 
paratively rare in Gloucestershire and in the midland counties. 
The local zones, or rather fossil-beds in Dorsetshire, yielding A. 
concavus and A. Sauzei, will be noticed further on. 
The " Sowerbyi-zone" which some authorities have separated 
from the zone of A. Murchisonce, is in trouble, for Mr. Buckman 
says there is considerable misconception regarding the type-form 
of the species.* We can, however, for stratigraphical purposes, 
well do without this sub-zone, with which the Lincolnshire Lime- 
stone has been generally grouped. In Dorsetshire Mr. Hudleston 
places the "Concavus or' Sowerbyi' zone" above the Murchi- 
soncE-zone : and, for the sake of convenience, he groups both of 
them together with the Opalinus- and Radians-zones in the 
Lower division of the Inferior Oolite. He however remarks that 
"there can be no doubt that the rich and characteristic fauna of 
the Inferior Oolite begins with the Murchisonce-zone, to which 
the opali?nts-zone is little more than an appendage. "t 
* Some specimens of " A. Smverbyi" are referred by Mr. Buckman to Harpoceras 
adicrum. Quart. Journ. Geol. Soc., vol. xxxvii. p. 602. 
f Quart. Journ. Geol. Soc., vol. xlix. (Proc.), p. 131 ; and Gasteropoda of the 
Inferior Oolite, p. 29. 
