RELATIONS TO OTHER BRITISH DEPOSITS. 55 



II. Neocomian Species : 



Ammonites Beudanti, Brong. Janira Morrisii. 



Plenrotomaria. Spondylus. 



Solarium. Cyprina Liyuriensis. 

 Aporrhais. ,, sp. 



Pecten orbicularis, Sby. 



This revised list does not however alter the value of the other 

 facts already brought forward by Mr Teall, but only strengthens 

 his conclusion that the Downham coprolite bed belongs to the 

 mammillaris zone of the southern Neocomians. 



Next, if we compare this bed with the Upware deposit we find 

 that the differences between the two are very numerous and 

 striking, whilst their resemblances are few. Both are phosphatic 

 nodule beds with yellowish sandy matrix, it is true, but all the 

 nodules at Upware are ' red coprolites ' — the pale yellowish choco- 

 late-like type, whereas at Downham Market there are, besides 

 those of the gault, two types both equally and strikingly different 

 from those of Upware (see ante), and indeed much more like 

 those of the Cambridge greensand. It is remarkable that they 

 are actually undistinguishable from those of the mammillaris zone 

 at Grandpre in the Ardennes. 



Now when we remember the great constancy in the characters 

 of the Neocomian nodules all along the western Neocomian out- 

 crop, and how great is their similarity in the other beds further 

 north, we shall probably be prepared to attach considerable import- 

 ance to the different character of the Downham coprolites. 



Lastly, the fossil evidences conclusively decide the matter, for 

 although the lithological characters of the two deposits are similar, 

 and the general physical conditions must have been so nearly the 

 same, the types of life being also similar, yet the only species 

 common to the two beds are Pecten orbicularis and Janira 

 Morrisii. Both of these are long-ranged types of no value what- 

 ever in detailed chronological comparison. 



We must therefore reject this bed from our Ironsand series, as 

 belonging to quite a distinct age, and as I am inclined to think, 

 pertaining to quite another series of events. For I look upon the 

 Ironsand group as belonging to the true Lower Greensand (Sand- 

 gate and Hythe series and perhaps base of Folkestone series), 

 while the Downham Market coprolite bed might, it seems to me, 



