1852.] LYELL BELGIAN TERTIARY FORMATIONS. 367 



of Maestricht and beds of the age of the Lower London Tertiaries. 

 The change in Europe from the Maestricht and Faxoe fauna to that 

 of the Lower Eocene is so vast as to prepare us for the discovery of 

 a long series of such intermediate rocks, characterized by species in 

 part new and in part cretaceous or tertiary, — formations in which 

 genera, hitherto [regarded, Hke the Cardiaster, as exclusively se- 

 condary, and others only known before as tertiary, may be found asso- 

 ciated. Instead of grouping all these monuments of an intervening 

 period as Cretaceous or as Eocene, it may be convenient to introduce 

 a new system, to which the calcaire pisolitique of France and the 

 Heersian and Lower Landenian of Belgium may be referred. 



In the Synoptical Table of tertiary formations, which has been 

 introduced into an early part of this paper (p. 279), it will be seen 

 that, so far as I have been able to ascertain, the Lower Landenian 

 and Heersian groups have no exact equivalents in the British Islands. 

 This opinion may require modification hereafter, when a fuller com- 

 parison has been instituted between the Lower Tertiary fossils of 

 England and those of Belgium. In the meantime, the place assigned 

 by M. Dumont to the Lower Landenian will be understood by con- 

 sulting his Tables already alluded to (p. 279, note) and printed as 

 Appendices Nos. I. and II. One of these was published in 1851, 

 and the other appears now for the first time, having been recently 

 communicated by the author, after his return from a geological ex- 

 cursion in England in the autumn of 1851. To him, and to all the 

 other geologists of Belgium with whom I had the pleasure of con- 

 ferring, I have to express my warmest thanks for their zealous and 

 effective cooperation. I must also avail myself of this opportunity 

 of acknowledging my obligations to MM. Nyst and De Koninck in 

 particular, for their unremitting attentions during my tour, and their 

 instructive correspondence since my return. In several of the principal 

 districts, the reader cannot fail to have perceived that I should have 

 made but little progress in the examination of their palaeontology 

 without such assistance as that afforded me at Antwerp by M. Nor- 

 bert de "VVael, at Brussels by Captain Le Hon, and in the Limburg 

 by M. Bosquet. These naturalists have enabled me to present to the 

 scientific world a more complete catalogue of the fossils of the several 

 regions studied by each of them, than had previously been printed ; 

 and in each case, when they generously placed at my disposal the 

 ample materials which it had cost them the labour of years to bring 

 together, they asked no other return for the gift than that I should 

 obtain the opinions of the best English palaeontologists on their fossils. 

 I have accordingly endeavoured by the aid of several friends, whose 

 names appear frequently in this memoir, especially those of Messrs. 

 S. V. Wood, Morris, Edwards, Rupert Jones, Hooker, and E. Forbes, 

 to discharge the debt incurred to my foreign fellow-labourers ; giving 

 the results of their comparison of Belgian and British fossils, respecting 

 which doubt and discussion had arisen, whether in reference to specific 

 characters, or to position in the geological series. 



It may also be well to state, before concluding, that, notwithstanding 

 the slight inequalities of level and the rarity of natural sections in a 



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