THE 



GEOLOGICAL MAGAZINE. 



NEW SERIES. DECADE IV. VOL. III. 



No. XII.— DECEMBER, 1896. 



OBIGINAL ABTICLES, 



I. — Some Notes on the Aptychi from the Upper Chalk. 



By H. P. Blackmore, M.D., F.G.S. 



(PLATE XVI.) 



IN 1853-6, when Mr. Sharpe published Lis monograph on the 

 Cretaceous Cephalopoda of England, the various species were 

 roughly placed according to the divisions of the Chalk formation as 

 described by Conybeare and Philips. This, unfortunately, led to 

 many mistakes : amongst others, Mr. Sharpe described Belemnitella 

 mucronata as occurring "everywhere in the Upper Chalk of the 

 South of England," whilst Belemnitella quadrata is only noticed as 

 occurring in the Middle Chalk of Kent, Surrey, and Sussex ; the 

 fact being that Belemnitella quadrata is not found in the Middle 

 Chalk, and Belemnitella mucronata is restricted to the highest zone 

 of the Upper Chalk. 



A careful study of the various Chalk beds by Barrois, Whitaker, 

 Price, Evans, and others has resulted in establishing the fact that 

 the Upper Chalk, which to the casual observer looks all alike, can 

 be easily subdivided into various zones, each zone being characterized 

 by the presence of certain typical fossils, amongst which the 

 Belemnites play an important part. In the upper beds are found 

 Belemnitella mucronata ; these are immediately followed by others 

 containing B. quadrata, and in the lower third of this zone is 

 a small band which contains B. lanceolata ; whilst still further down 

 in the'Marsupite zone is found the small B. vera. 



UPPER CHALK ZONES IN THE NEIGHBOURHOOD OF SALISBURY. 



DECADE IV. VOL. III. NO. XII. 



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