52 INFERIOR OOLITE AMMONITES. 



are best classed as the lower part of the Opalinum-zone. Among other things, 

 I have obtained from them Lytoc. torulosum, Terebratula infra-oolitica, and Rhyn- 

 chonella cynocephala. The last-named fossil occurs abundantly with some 

 other Rhynchonellce, Waldheimice, Grammocerata, and very rarely Lioc. opalinum. 

 I am inclined to think that the Freestone-beds of Ham Hill containing Rhyncho- 

 nella cynocephala are upon the horizon of this Opalinum-zone taken, as above, 

 in a wide sense. 



The identity of the Yeovil Sands below this horizon with the similar sands of 

 the Cotteswolds appears probable, the fauna of what I call the Striatulum-sub- 

 zone in Gloucestershire seeming to be entirely absent. Therefore it is probable 

 that the whole of this part of the Yeovil Sands, 1 their " main mass," would be 

 below the zone of Am. jurensis according to Oppel. But, notwithstanding their 

 apparent identity with the Ootteswold Sands, we do not find in the shelly 

 bands the extensive Ammonite fauna which we meet with in those bands in 

 the Cotteswolds. In fact, I do not think that the fossiliferous bands in the two 

 series contain an Ammonite in common. The Yeovil Sands contain one having 

 a very great resemblance to Qramm. Moorei, Lycett, an Ammonite which in 

 Gloucestershire is characteristic of the middle part of the Cephalopoda-bed C", 

 and of which I have seen no trace in the Cotteswold Sands. The fact is that, 

 looking at the Ammonite fauna, the Cotteswold Sands are extremely well stocked, 

 and there should be little question of their true position when these Ammonites 

 have been worked out. The Sands at Midford and in Dorset are not at all well- 

 furnished in this way, and hence the trouble that we experience. This state of 

 things is exactly reversed when we compare the Inferior-Oolite Limestone of 

 Dorset and Gloucestershire. 



The bed which I have numbered " 3 " in my extract from Mr. Sharpe's section of 

 the Northampton Sand at Old Duston is the one from which he quotes Am. 

 opalinus, and this is also confirmed by Mr. B. Thompson, F.G.S., who has sent me 

 specimens of Lioceras opalinum and Lioceras comptum, from this horizon at the 

 same place. 2 Their matrix can scarcely be called sandy, but is a calcareous 

 stone of a bluish-green colour with lighter oolitic grains, and is similar to that 

 in which Lioc. opalinum occurs at Burton Bradstock. Mr. Sharpe's two sections 

 will explain its position with regard to the Upper Lias Clay, and to the beds above. 



From the Bed B of Mr. Walford's section, 3 Otley Hill, near Hook 

 Norton, Oxfordshire, I have through his kindness seen specimens of Lioceras 



1 At Yeovil, Bradford Abbas, &c, there seems to be no trace of the Opalinum-beds, and, therefore, 

 the whole of the sands there may be below that horizon. 



2 This locality is sometimes called " New Duston " on account of some new houses that have 

 sprung up round the old workings. 



3 " On the Trigonise of North Oxfordshire," ' Quart. Journ. Geol. Soc.,' vol. xli, 1885, p. 38. 



