210 
BUCKMAN : UPPER TOARCIAN BEDS. 
tion for dating precisely the deposits between the Dogger and 
the Striat2ilus Shales. 
The Yellow Beds are contemporaneous with the Ironshot 
8tone of the Cotteswold Cephalopod Bed {Dumortierice) : the 
Ammonites are Dumortieria externicostata (Branco). and D. aff. 
mvlticostata , S. Buckman. 
The Grey Beds yield Hudlestonia spp. and Phlyseogrammo- 
ceras dispansum (Lycett). The latter Ammonite makes the 
Grey Beds equivalent to the Blackish Mudstone of the Cotteswolds 
(dispansi) ; but the Hudlestonia spp. are quoted from the 
Dumortieria-Zone of the Cotteswolds and Dispansum-7.one of the 
Yeovil district. This suggests that the Hudlestonioe are on the 
border between the Dispansum- and Dumortieria-^edfi ; and that 
the true succession in time may be — 
Dumortieria 
Hudlestonia 
Phlyseogr. dispansum. 
This suggests a point for future investigation where the 
strata are thick : it is difficult to settle in the Cotteswold Hills 
where the beds are so thin. 
Below the Gre}^ Beds are the StriatulusShales, said to be 
from 50 to 70 feet thick. It has long been known that the 
Striatulu^ Shales are in part equivalent to the Bottom stone of 
the Cotteswolds {striatuli) ; but there is no evidence 3'et of 
Haugia eseri nor of the fauna of the Linseed Bed {Pseudogrammo- 
ceras ^^^dicum and allies). There is. however, one interesting 
piece of evidence among the Simpson tj^pes : sent as his A . latescens 
is a Pseudogrammoceras of the quadratum type, near to P. suh- 
quadratum (S. Buckman), forms of struckmanni date from the 
Yellow Stone of the Cotteswolds. The mineral condition of 
A. latescens shews that it cannot be later than the Striatulus- 
Shales ; and it suggests that part of these Shales is of struckmanni 
date. 
There was sent to me many years ago by the late W. H. 
Hudleston a specimen of Phlyseogr ammoceras orhignyi (S. 
Buckman) as from the Striatulus Shdles. As this species is an 
associate of P. dispansum in the Cotteswolds, it would seem as if 
the bottom of the Grey Beds and the top of the StriatulusShdles 
may have to ])e dated as dispansi hemera. An almost unidentifi- 
