HYPERLIOCERAS. 91 



Abbas and the neighbourhood were obtained by Mr. Witchell from the same 

 horizon as these species of Hyperlioceras. By the kind permission of him and his 

 family I have frequently been able to examine and identify all these specimens. 



These discoveries are of the highest importance for the correlation of the beds 

 of the Inferior Oolite in the Cotteswolds with those of Dorset ; first, because the 

 Gryphite-grit is an horizon well-marked and easily recognised over a wide extent 

 of country ; and secondly, because Ammonite-remains are very scarce in the 

 Cotteswolds. The conclusion which we naturally draw from this similarity of the 

 Ammonite-fauna is that the Gryphite-grit is of the same age as the Bed No. 5 (sec- 

 tion, page 5) at Bradford Abbas, and that the Gryphite-grit consequently belongs 

 to the so-called Sowerbyi-zone on the same horizon as the Concavum-beds. This 

 idea forced itself upon me lately, when, during some work among the rocks of the 

 North Cotteswolds, 1 I found in strata but little below the horizon of the Gryphite- 

 grit Ammonites which I recognised as characteristic species for the Bradford- 

 Abbas Concavum-beds ; and my opinions became confirmed when Mr. Witchell 

 drew my attention to what he had discovered near Stroud. My father 2 always 

 argued in support of a somewhat similar opinion, if we consider that the most 

 important member of the so-called "Dorset Cephalopod-bed " is the Sowerbyi-zone 

 (Concavum-beds) at Bradford Abbas; and I found that Dr. Waagen 3 had put 

 forward what is practically the same view as mine. Dr. Wright 4 , however, and 

 Prof. Judd, B placed the Gryphite-grit in the zone of Am. Parlcinsoni ; and Mr. 

 Witchell 6 placed it in the zone of Am. Humphriesianus. With these determinations 

 the Ammonite-fauna does not, in my opinion, agree; and, whilst recognising the 

 fact that the next horizon above the Gryphite-grit, namely, the Upper Trigonia- 

 grit, certainly belongs to the zone of Am. Parlcinsoni, I have to come to the conclusion 

 that the zone of Am. Humphriesianus has not yet been detected in the Cotteswolds. 



Hyperlioceras is, as I have said, peculiar to the Concavum-beds, and at present 

 I have not found at a higher horizon any species of Ammonites which belong 

 to this genus, or could be supposed to have descended from it. Though not 

 uncommon in the Bradford- Abbas district, the genus attains to nothing like the 

 importance of Lioceras. 



Most of the species of Hyperlioceras, as well as Lioceras intermedium, have 

 been quoted from Dorset by the name of Am. Iseviusculus, chiefly on account of the 



1 " The Inferior Oolite between Andoversford and Bourton-on-the-"Water," ' Proc. Cotteswold Field 

 Club,' vol. ix, part 2, p. 130, 1887. 



2 " On the so-called Midford Sands," ' Quart. Journ. Geol. Soc.,' p. 738, 1879. 



3 " Ueber die Zone dea Am. Sowerbyi," « Geogn. pal. Beitr.' Bd. i, Heft 3, p. 579, 1867. 



* "The Inferior Oolite," ' Quart. Journ Geol. Soc.,' vol. xvi, p. 37, et seq., 1860; " Monog. Lias 

 Amm.," ' Pal. Soc,' vol. xxxiii, pp. 150, 154, &c. ; also in several other papers. 



5 "The Geology of Eutland," 'Memoirs of the Geological Survey,' p. 8, 1875. 



6 " The Geology of Stroud," p. 39, 1882. 



