72 FOREIGN RELATIONS OF THE 



similarity of the sponge faunas of our phosphatic beds and Essen 

 in Westphalia 1 deserves to be mentioned, although the rock of this 

 latter place is generally referred to a much higher horizon, viz. the 

 Tourtia or Cenomanian. Our Peromelia furcata and Elasmostoma 

 pezisa are I have no doubt the same as the original Essen species, 

 and E. acutimargo and the curious Pachytiloda have also very 

 near representatives amongst the Essen forms. 



The great series of brownish yellow sandstones of the Teutobur- 

 ger Wald, near Bielefeld, shews no special palseontological affinity 

 to our Upper Neocomian (Low r er Greensand) sands. 



In the country around Hanover we again meet with a great 

 Lower Cretaceous freshwater series like our Vectian type of 

 Wealden; but the overlying clays shew little community either of 

 lithological or palseontological character with our ironsand series; 

 nor indeed with any part of the Vectian cretaceous group. 



Still further east at Salzgitter, south of Brunswick, we meet 

 with some open-air iron-workings in the Neocomian rocks which 

 are placed by Professor Judd in his Middle Neocomian group. The 

 similarity of these beds to the oolitic iron-beds of Lincolnshire has 

 been pointed out by Mr Judd ( Quart. Journ. Geol. Soc. 1870, p. 330), 

 who writes, "The English and German ironstones are, both as rock 

 specimens and in polished sections under the microscope, quite 

 undistinguishable in their characters." Specimens of Pecten ductus 

 from the two areas are almost identical in every respect 2 . 



As compared with the Upware bed this rock is interesting as 



? The fossils of this bed were found in the course of the workings for coal 

 around Essen ; these having now ceased the cretaceous fossils are difficult to obtain. 



2 Some of the iron ore is as perfectly oolitic in appearance as the well-known 

 Pisolitic ironstone of Lincolnshire, the grains being round and regular, and speci- 

 mens may be obtained identical with the Lincolnshire rock. But generally certain 

 larger angular and sub-angular fragments occur scattered through the rock, and it 

 frequently passes into a rock composed of a blue clay matrix, crowded with iron 

 fragments, most of which are markedly angular. Now some of these latter are 

 quite evidently fragmentary rocks, the iron particles being more or less worn 

 fragments, of irregular shape. Again this type passes by perfect gradation into the 

 most thoroughly rounded oolitic-looking rocks. As a result of my work in this 

 quarry I became convinced that this rock is no true oolite, but is made up of the 

 rounded and polished fragments of iron derived from older rocks ; perhaps from the 

 destruction of the Brown Jura formation. This is also the opinion of Herr Gebeimer 

 von Strombeck of Brunswick. To such rocks I apply the term ' pseudoolitic.' An 

 examination of thin sections confirms this opinion as a whole, but discloses also a 

 number of true oolitic grains in most specimens. 



