part 1] jurassic chronology : lias. 103 



2nd Capricorn, 3rd Capricorn, clavcei ; and, because the middle two 

 terms were missing in Dorset, he claimed a non-sequence. But, so 

 far as the evidence went, it was equally arguable, and surely far 

 more natural, to suppose, that the 2nd Capricorn was contempo- 

 raneous with the latoecosta-, and the 3rd Capricorn with the davoei- 

 horizon ; and this would do away with the necessity for calling in 

 a non-sequence in Dorset where no evidence for it appeared. 

 Though not prepared always to go so far as the Author, the speaker 

 wished to acknowledge the stimulus of his work, as well as the 

 encouragement and help that he had received personally from the 

 Author. 



The Secretary read the following contribution to the Discussion 

 sent by Dr. A. E. Trueman : — 



' Through the kindness of the Author, I have been allowed to read his paper 

 in manuscript. A valuable feature of this communication is the further 

 application of the methods of faunal analysis. The paper is perhaps most 

 interesting- however, because the Author has stated so clearly his ideas on 

 correlation, and has given a fuller explanation of his " law of dissimilar 

 faunas " ; the facts now adduced by the Author seem to prove conclusively 

 that dissimilar faunas are very rarely due to different geographical conditions, 

 but usually indicate that the deposits are of different age. It appears to me,, 

 however, that certain species may have had a restricted distribution within 

 the British Liassic seas, and, while the Author's methods are of very general 

 application, careful collecting may in some cases yield more accurate results.. 

 I ought, however, to point out that, wherever Liassic horizons have recently 

 been studied by detailed collecting, the results have confirmed the conclusions 

 at which the Author had arrived from his faunal analyses. 



' The importance of the minute subdivisions that are made possible by this 

 work cannot be overestimated. Quite apart from their biological interest, 

 they are becoming of great value to the economic geologist. The Author 

 showed some years ago the connexion existing between Jurassic anticlines and 

 synclines and hidden coalfields ; in a forthcoming paper Prof. Cox and I have 

 endeavoured to trace such Jurassic movements, but we have found that only 

 the thinnest zones can be used for the purpose, and that, generally speaking - , 

 there is a great lack of sufficient detail. The recpiisite evidence can 

 only be obtained by using methods such as the Author has so successfully- 

 developed.' 



mutt; 



FEB 12 1 



Q. J. G. S. No. 302. 



