566 Correspondence. 



M. von Koenen starts with what is calci^lated to produce an 

 erroneous impression. At page 504 he says, " Mr. G. A. has published 

 a number of observations made at Antwerp during Ms short stay." Of 

 himself he says, by way of contrast, " I have visited Antwerp on five 

 separate occasions, in three different years ;" but had he read my paper 

 with more attention than he has, he would have seen that T had been 

 there repeatedly ; and what is more to the point, that I had seen 

 the sections at Edeghem in 1861 (p. 234), when the extent of open 

 work was much more favourable for geological observations than 

 in 1865. 



He complains (p. 505) that I do not follow the divisions of any 

 of the authors who have described those beds ; if this means that I 

 have not used such terms as Oligocene, Miocene (GtEOl. Mag., p. 507), 

 it is true, but it was not from ignorance ; rather from an old conviction 

 that such a system of nomenclature was based in vague, mistaken, 

 and theoretical views. He is incorrect, however, when he states 

 that I have disregarded old names. I took, what I still consider to 

 be, the natural division of the Belgic Kainozoic beds — that of M. 

 Dumont and M. Nyst. The natural system in geology and paleeon- 

 tology is that which describes old sea-beds and their contents, 

 according to the guidance which the naturalist and hydrographer 

 have derived from the dredge and sounding lead ; in place of this, 

 the artificial systematists have endeavoured to set up what are 

 merely convenient Museum arrangements. 



Some of M. V. Koenen's sentences are contradictions rather than 

 objections, p. 505, " Barton Clay does not correspond in age with 

 Rupel Clay." Waiting for better evidence to the contrary, it seems to 

 me that the approximation of the purely marine clays of Eupelmonde 

 to those of Barton is closer than that which can be established be- 

 tween any two deep sea mud-beds of the English and Belgic Num- 

 mulitic formations. It may be, and must be, that a freshwater 

 formation in one place is the equivalent of a purely deep-sea series 

 in another, the Physical Geologist may some day arrive at their 

 arrangements, but not so the Cabinet Conchologist. Another short 

 phrase used by M. Von Koenen at p. 505, is also calculated to mis- 

 lead : " The Tertiary beds of Cassel, Luithorst, Freden, and Diekholz, 



which he puts into the upper Kaniozoic, are coeval with the 



Grafenberg and Sternberg Sandstones which he puts into the 

 Tongrien." Put in this way, it certainly represents me as writing 

 nonsense, but I wrote nothing of the kind. The reference given is 

 to a note, in which I state " that the map of the Crag Sea has been 

 drawn so as to include the Upper Kainozoic formation near Cassel, 

 etc." There is an extension of sea-bed thus far into Hesse with the 

 following fauna : — 



Solen ensis, Mactra triangula, Corhula nucleus, G. revoluta, C cus- 

 'pidata, Tellina distorta, Astarte incrassata, Cyprina Islandica, Venus 

 plicata ? Cardnim papillosum, Isocardia cor, Area diluvii, A. noa, 

 Nucida sulcata, N. margaritacea, N. minuta, Galyptrcea vulgaris, Bulla 

 alriada, B. ovidata, B. lignaria, B. LajonJcaireana, B. acuminata, 

 Eidima suhulata, E. nitida, Natica castanea, Turritella communis, T. 



