-IK) T. 0. Bofiivortli—Zonon q/f/ic Loiirr Chalk. 



tlio niirwoll Uook, ami contains the A. vnriaus zone fanna. The 

 fossils are extionioly nnniorous in this IhhI. oonsistini; iirinoipally 

 of hiri;t> specimens of /». M(tiitrll!tiim, Scrpitia nmhonnta, Tfiebrn- 

 iuliua nodnlosa, and Cidnria dinttimilis. 



HI. On JTolastkr tukces'sis. 



Tn T)orset and Devon this fossil is plentiful in the beds above the 

 A. vtviaus zotie, Jf. Htibcjlohosus itself beinj; absent. //. tri'cenxis is 

 almost oontined to the zone and could well be used as the zone fossil. 



In Hants, Sussex. Kent, and Isle of Wis;ht, tliis fossil is common 

 throuuhout the zone from base to summit, and is only occasionally 

 found in the riialk IMarl. 



In Yorkshire //. irfrciisls is not found. 



In Ijinoolnshire //. tirccnttits is found above the Burwell Rock, and 

 it is also recorded from the Chalk Marl, but I do not know whether 

 it is common at that horizon. 



In Cambridgeshire Jf. trecrnsia is not yet recorded except from 

 Shelford. in the (.Jeneral Memoir (op. cit.. liHVi). But examination of 

 the Lower CMialk of this county during the past three years has shown 

 to me that this fossil is reniarkably abundant, being much more 

 common than 11. stthijlobosus. In fact, there appear to be two very 

 distinct zi>nes in Cambriilgesliire in this 80 feet of Chalk — the 

 upper half (about 40 feet) abounding in If. twcensts. but with 

 no //. suhtjJohosHS ; the lower half with 11. suhijhbosua and no 

 II. trtct'iinis. 



1 have found 11. tifcnisls in the great pit at Cherry-Hinton in the 

 upper part of the Lower Chalk, which hjis not been worked for many 

 voars. also at Shelt'ord in abundance, and most plentifully in the pit 

 on the Golf Links. In this latter locality the zone of Jc/i»ec(i)H(i.i; 

 jih'iiuit and the upper oo feet of the so-called JJ. snbijloboans zone are 

 tpiarried. Fossils are on the whole very scarce, but I have found 

 J{. Inccusis in sitii from the bottom of the section up to within a foot 

 of the Actiuocamax ph'uus (z= Ji. ylrna) zone. I have also had all the 

 fossils from the workmen for the past two years. 



The following is a list of the species, with the number of specimens 

 obtained : — 



FlSCKS. 



