GLOUCESTER, DORSET, AXI) SOMERSET. 3 



As, however, the shells of the 2 feet 6 inches bed, described as 

 the Cephalopoda-bed at Bradford and other places in Dorset, are 

 identical with those at Dundry, and at both Bradford and Dundry 

 it contains with others 



Ammonites Parkinsoni, Sow. (A. Ammonites Murchisonse, Sow. 



dorsetensis, Wr.\ jurensis, Ziet, 



Humphresianus, Souk 



we conclude that the Cephalopoda-beds at Bradford and Dundry 

 are on the same horizon, and, further, that neither the one nor the 

 other has the slightest connexion with the Cephalopoda-bed of 

 Gloucestershire ; and if this be so, the fact that the four Ammonites 

 just quoted have been made representatives of four distinct zones, 

 will be a difficult problem to solve for those who implicitly believe 

 in zones. 



One of the more recent papers, " On the Correlation of the several 

 subdivisions of the Inferior Oolite in the middle and south of Eng- 

 land," is by Dr. Holl, who concludes that the true position of our 

 Dorset and Somerset beds is higher in the series than is stated by 

 the geologists just quoted, and " that they are, in fact, the southern 

 extensions of the Upper and Lower Bagstones of Mr. Hull, the 

 uppermost of which is not represented in the typical section at 

 Leckhampton, having risen above the level of the country, and 

 cropped out before reaching the brow of the hills"*. 



We agree with this view, except that we consider the Dorset 

 Cephalopoda-bed the equivalent of the Gryphite Grit at Leck- 

 hampton, and that the roughly bedded stone above is the repre- 

 sentative of the Trigonia Grit of Cold Comfort. The constant 

 presence of the same typical Ammonites on the top of Leckhampton 

 hill and in the Bradford Abbas quarries seems to prove this assertion, 

 such as 



Ammonites Sowerbyi, Miller. Ammonites concavus, Sow., M.C. 



Brocchii, Sow., M.C. subradiatus, Sow., M.C. 



Humphresianus, Sow., M.C. Murchisonae, Sow., M.C. 



Parkinsoni, Sow., M.C. 



and others. 



From this, then, it follows that, while the Gloucestershire Cepha- 

 lopoda-bed is at the base of the Inferior Oolite or top of the Upper 

 Lias, the Dorset Cephalopoda-bed is near the top of the former ; and 

 yet they have not only been confounded the one with the other, but 

 this position has been supported by the similarity, not identity, of 

 the Cephalopoda, which, indeed, have been held to point to Lias 

 rather than to Oolite. 



Dr. Holl's view of the case seems to be, that while we have thus 

 the Upper Bagstones, the lower members of the Inferior Oolite are 

 deemed to be absent ; for he says : — 



" On the southern side of the Mendips the Inferior Oolite nowhere 



* Quart. Journ. Geol. Soc. vol. xix. (1863) p. 307. 



it 2 



