F. A. Bedwell — Ammonites in Thanet Cliffs. 



17 



vidual flints seldom run large, and are separated from each other, gene- 

 rally by a foot of chalk, frequently by much more, but seldom by less. 

 The minimum distance below it at which I have found a specimen is 

 4ft. 6in. and the maximum 60ft. Sin. Eeferring to this band as a "datum 

 line," and grouping in six different "averages" all the 89 various 

 measurements so taken, the following particulars are obtained. 

 Table of Average Depths op Ammonites below "Datum Line." 



No. of 

 Specimens. 



Average depth 



below 

 "datum line." 



Greatest 



depth. 



Least Depth. 



Depth 

 Unknown. 





ft. in. 



ft. 



in. 



ft. in. 





8 



6 8 



8 







4 6 





32 



12 



14 



6 



9 





6 



16 8 



17 



9 



15 6 





25 



20 2 



22 



3 



18 





11 



25 2 



27 



5 



23 5 





4 



32 9 



35 







31 1 





1 



46 9 







..• ••• 





1 



60 3 





... 









1 

 89 























It will be seen from these figures that the 12-foot line and the 20- 

 foot line both represent periods of special maximum development. 

 Indeed seven of the specimens on the 12-foot line lie in a space of 

 200 yards, and three of them almost touch each other, and look very 

 much as if they had actually " died together." 



The large majority of the specimens are referable to Ammonites 

 leptophyllus. I identified thirty-five of this kind. I also identified four 

 as A. Lewesiensis, and one as A. peramplus.^ The rest are indistinct. 



In addition to these particulars, I am also able to give exact detailed 



Fig. 1. — Outline of Isle of Thanet, showing the distribution of Ammonites along the coast. 



^ But query if these three forms are not identical. I have a flint cast in my possession 

 which looks very much as if it united all three forms in its markings. See also Sharpe's 

 Mollusca, Pal. Soc. 



DECADE II. — VOL. I. — NO. I. 2 



