﻿Vol. 66.] CEKTAIX JUKASSIC STKATA OP SOUTH DOESET. S5 



Young & Bird, A.fabalis, A. beani, A. phillipsi, A. rudis, Simpson, 

 are species of the Lillia-Haugia series, indicative of deposits of 

 lilli-variabilis dates : they are fine specimens too. There is also 

 Hawjia patelliformis 1 = Ammonites obliquatus, Simpson, paws, noii 

 Young;, indicative of variabilis beds. 



I have not yet seen the type of Hildoceras hildense (Young & 

 Bird) ; but, from their figure, it appears to be a species of the lilli 

 beds, from its likeness to my H. semipolitum which is so charac- 

 teristic. The Ammonites 7iildensis, Simpson, is another species ; 

 it occurs in the Jet Rock, and has no likeness to Young & Bird's 

 figure. 



In Divisions 2 & 3 Simpson records no Ammonites : Tate & 

 Blake appear to have Ammonites bifrons from about this level. 



In Division -i there is evidence of a deposit made during a period 

 of time of which there is not evidence in the south — a hemera 

 of ovatus. However, this is not the true Ammonites ovatus of 

 Young & Bird's first edition, though it is of their second : they had 

 a happy knack of changing names. 



The Hard Shale and the Jet Rock give nearly 70 feet of deposit 

 during the falciferi hemera ; unless, as seems possible, this can and 

 ought to be subdivided into an earlier and a later period. 2 



Interest now centres in the Grey Shales, or annidatus beds of 

 Tate & Blake. First, the Ammonites annidatus is wrongly named : 

 it is A. tenuicostatus, Young & Bird : with it occurs A. semicelatus, 

 Simpson, and both belong to Dactylioceras. It is best to call this 

 the deposit of tenuicostati hemera. 



The point that now remains for consideration is this : — "What 

 relation does the stratum of tenuicostatus bear to the stratum of 

 Seguenziceras acutum (Tate) — the Transition Bed of the Midlands ? 

 Is it of the same date, or earlier, or later ? The question is difficult 

 to answer, because it is impossible to trust the identifications of 

 the Dactylioceras Ammonites. To answer this question, it may 

 I)e advisable to consider the relationship of the Yorkshire and Mid- 

 land Toarcian strata ; and this, through the kindness of Mr. Beeby 

 Thompson, I am able to do in greater detail than when the pre- 

 ceding paragraphs were first penned. 



(b) Yorkshire and other Districts compared. 



Since this paper was written, Mr. Thompson, in answer to 

 certain queries which I addressed to him with regard to the corre- 

 lation of the Northamptonshire and Yorkshire Upper Lias, placed 

 in my hands some MS. of a paper just printed off by the Geologists' 

 Association. This MS. is valuable, for it shows that Mr. Thompson, 

 from his study of the Northamptonshire Upper Lias, finds it necessary 

 to increase the number of zones, a process that I was contemplating 

 for this paper from a consideration of the records of the Yorkshire 

 strata . 



1 ' Monogr. Inf. Ool. Amm.' Suppl. pi. iii, figs. 1-3. 



2 Mr. Thompson has done this since these words were penned, see later in 

 this page. 



