4:12 ME. s. s. BrcKMAZs" ox [vol. Ixxviii, 



matrix, and the Grammoceras-sfriatuluin forms are in a yellowish 

 deposit. 



The second theory requires that Sammatoceras or some contem- 

 porary should be found low in the Watton-Cliff Junction-Bed. This 

 theory does not account for the white matrix of the presumed pre- 

 faJciferum Hildoceratids. found by Mr. Jackson towards the top 

 of the bed. And it involves the following corollaries : (^a) that 

 any strata deposited in the Watton-CIiff locahty dui'ing the 

 makins; of the Junction-Bed of the Western Cliffs and elsewhere 

 were broken up and redeposited during Sammatoceras time; 

 (&) that all such strata were removed, and then that the Samma- 

 toceras sea had access to exposed strata of tliorncomhiensis, pre- 

 exaratum, falciferum, hifrons, striatuhim, and other hemera;, in 

 order to gather materials for the making of the bed — to a certain 

 extent layers 2, 3, & -4 give evidence that som^ po]-tions of such 

 sti-ata were available for supplies ; ( c) that all the f aunal contents 

 of the Watton Bed which are of older date than Sammatoceras 

 have been derived. 



The third theory sounds rather elaborate, but it seems helpful 

 in many ways : {a) it will account for the ^^vq -falciferum Hildo- 

 ceratids havincr a white-stone matrix, so that thev have the same 

 matrix after derivation as that in which they are enclosed; (Z*) it 

 synchronizes this j)resu.med -pTe-e.raratin/i deposit of fine-grained 

 lithographic stone with the paper-shales of Xorth Gloucestershire — 

 as, for instance, Alderton-Dumbleton : and such synchronization 

 of two fine-grained, tliinly-laminated dejDOsits is rather an interest- 

 ing point ; (c) it accounts for the absence, except as derivatives, 

 of deposits of ^ostfalciferum to ^re-Sammatoceras hemerse, and 

 also for their irregularity ; ((/) it brings into accord the commence- 

 ment of the second white-stone deposit at AVatton Cliif with the 

 same deposit at Bothenhampton — there it is ])0$t-striatif7u/n, 

 presumably Hammatoceras ; at AVatton Cliff it is ])Ost-striati/Iinn 

 certainly Sammatoceras, so far as layer 4 is concerned. 



If, however, this theory be correct, then there will he the 

 foUo^ving corollaries awaiting acceptance : — 



{a) The presumed -pre falciferum Hildoceratids should be found 

 in the basal part of the blocks : unfortunately, this basal part is 

 the most difficult portion to attack ; i'h) this -pre -falcffer urn 

 white-stone deposit has been removed by denudation from the 

 Junction-Bed of the Western Cliffs and of other places : there 

 certainly is a non-sequence in the required position — both stratal 

 and faunal failure ; this is not asking too much, because denuda- 

 tion of the -prefalciferum deposits occurs over a considerable 

 area — south of Xorth G-loucestershire they are only preserved in 

 patches, and in stratal sequence those are often incomplete : ( c) that 

 the main constituents of the Junction-Bed of the Western 

 Cliffs were not deposited in the Watton Bed in a regular order, 

 but are only represented by chance f aunal and stratal elements in 



