VI PREFACE. 



A considerable number of the species from Upware and Brick- 

 hill prove to be as yet undescribed, a fact which was to be expected 

 in so isolated and peculiar a deposit so thoroughly ' episodal ' as 

 Mr Blake would express it as that of Upware and Brickhill. 



In working with the already known species the reference to the 

 original figure has always been made; and I have also given, when 

 possible, references to some few other good figures and descriptions 

 such as may be most useful or accessible to working Geologists ; 

 but no attempt is made to work out the complete synonymy of 

 each species. Such a work can indeed rarely be quite satisfactory, 

 depending, as it must do, to so great an extent upon the com- 

 parison of figures and descriptions only. 



In the nomenclature it will be found that I have in several 

 cases adopted names and used them as of varietal value and not 

 as distinct species- e.g., Ostrea frons, Park, var. macroptera, 

 Sowerby, for it appears to me that such a trinomial system is a 

 growing necessity in many of the larger generic groups, both in 

 recent and fossil organisms. 



Amongst the matters of more general interest worked out in 

 these pages will be found : 



(1) The close palseontological relationship of the Ironsand 

 and Phosphatic series as found at Upware, Potton, Brickhill, and 

 Farringdon. 



(2) The special character of the native forms of life in our 

 Lower Greensand Phosphatic beds : their richness in Brachio- 

 po4s, Polyzoa, and Sponges. 



(3) The influence of different physical conditions upon the 

 characters of the faunas as illustrated by the Upware and Potton 

 fossils (p. 48). 



(4) The presence at Upware of a little batch of species 

 which flourished long afterwards in the Upper Chalk period in 

 the neighbourhood of Dresden (pp. 20, 119), 



