320 DR. A. M. DAVIES AND MR. J. PRINGLE ON [June I9T3r 



about 300 feet at once made clear the importance of the non- 

 sequence between Oolites and Lias. Although no ammonite was 

 then found at any higher level, the presence of the same Nuculancc 

 at intervals throughout these 100 feet of shale indicated that there 

 could be no other break in the sequence, and suggested that no 

 stage higher than Charmouthian was present. Long afterwards it 

 was discovered that a section of core which had been placed near 

 the Oxford-Clay cores, and had been taken for part of them, con- 

 tained the same species of Nuculana as that already mentioned. 

 Fragmentary ammonites which it also contained were at once- 

 submitted to Mr. Buckman, who identified them as belonging to 

 the algovianum (lower margaritatus) zone. It became evident that 

 the cores had been displaced, and doubt was thus thrown upon th& 

 record of depth at which other fossils had been collected. This 

 doubt is of little consequence, except in regard to those recorded 

 as coming from the depth of 210 feet : in that case it becomes un- 

 certain whether they come from below, or from above, the horizon 

 adopted as the boundary between Domerian and Charmouthian. 



Except for three interruptions, the Lias from top to bottom, 240 

 feet in all, appears to consist of shales of very uniform character. 

 Those near the base are distinctly less fissile than those towards 

 the top, but otherwise the only differences noted are in colour ;, 

 and it may be doubted whether these really exist to the extent 

 recorded, for specimens which at the time of collecting were 

 noted as brown have by drying become pale grey. Although few 

 cores were seen between 300 and 430-feet, there is no reason to 

 suppose that any great variation occurred between those depths.. 

 Septaria were met with at several levels. 



The three interruptions already mentioned are a bed of sand, 3 feet 

 thick, reported near the top, aud two fossiliferous limestones (each 

 some 2k feet thick), at about 354 and 440 feet respectively. 



The evidence of the misplaced core proves the presence of the 

 algovianum zone. It is probable that this came from immediately 

 below the Chipping-Norton Limestone, because there is no evidence 

 of any higher zone of Lias. In the absence of any other evidence 

 it will be convenient to take the bed of sand at 211-214 feet as- 

 marking the base of the Domerian, which would then be represented 

 by the topmost 11 feet only. 



Of the zones of the Charmouthian, only two are clearly proved 

 present — ammonites of the striatum zone were found at 300 and 

 354 feet, and brachiopods of the jamesoni zone at 438-440 feet. 

 It is reasonable to assume that some part of the 86 feet from 

 214 to 300 belongs to the capricornus zone, and some part of the 

 84 feet between 354 and 438 to the valdani zone. The minimum 

 thickness of the striatum zone is 55 feet (300 to 354 inclusive). 



The fossiliferous limestone near the base (and with it, presumably, 

 the underlying 3 feet of unfossiliferous clay) may safely be ascribed 

 to the jamesoni zone, on the evidence of its brachiopod fauna. 

 The most abundant form is ZeilJeria ivaterJiousei (Davidson), the 

 specimens being in precise agreement with some from the jamesoni 



