part 4] jUEASSic chboxology : lias. 257 



9. JuEASSic CHEOJfOLOGY: I — LiAs. By S. S. BucK^y«^J^S?[Xl^^.'^^ '/7^^ 



(Head June 6th, 1917.) /A> ^<i^^ 



[Plates XXYI-XXXL] {"^ /^l^y j ^^^^ ^ 



Contents. \ -^ ^ 



I. Introduction \^^^a/ MuS^N^^! 



II. Yeovilian and Wkitbian 251 



III. Domerian 260 



IV. Charmouthian 262 



(1) Hwiccian 263 



(2) Wessexian 266 



(3) Eaasayan 267 



Y. Sinemurian 268 



(1) Deiran 269 



(2) Mercian 271 



(3) Lymian 273 



VI. Summary 275 



VII. Conclusion 275 



Appendices : — 



I. Zonal Sequence in the Lower Lias, by J. W. Tutcher. 278 



II. Mayer-Eymar's StratigrapMcal Terms 282 



III. Palaeontology. 



(a) Introduction 284 



[h) Descriptions of Species 284 



(c) Geological Inferences 307 



(d) Synopsis and Index Details 315 



(e) Concerning some of Wright's figured Ammonites. 318 



I. I^yTEODUCTIOJf. 



DuEiXG the last few years ^ I have been engaged to examine a 

 series of ammonites and brachiopods — some thousands of speci- 

 mens — collected by the officers of the Greological Survey of Scotland 

 in the islands of the Inner Hebrides off the west coast of Scotland — 

 Mull, Skye, Raasay. As the thickness of these Oolite-Lias deposits 

 is very considerable and s|)ecimens are in many places numerous, 

 the faunal sequence is often obsej'vable to great advantage ; and, as 

 new faunal elements have been disclosed in some cases, the Oolite- 

 Lias chronology requires a certain amount of elaboration and 

 revision. By the kind permission of the Director of the Greological 

 Survey I am allowed to give an abstract of certain results. These 

 data, when compared with those which have been gradual^ accu- 

 mulating about other districts, throw an interesting light on the 

 faunal sequence in certain strata, and, though admitting that all 

 suppositions are not yet proved, I venture to offer to the Society 

 an epitome of evidence and surmise with the idea of drawing the 

 attention of other Avorkers to the particular points about whicii 

 further investigation is desirable. 



"' This paper was commenced in the winter of 1914-15. 

 Q. J. G. S. No. 292. T 



