Reviews and Notices of Books. 339 



This remarkable group, commencing at Essen and Miihlhein on 

 the Rhine, and whence were derived so many of the cretaceous 

 forms described by Mr Goldfuss, ranges along the outline of the 

 palaeozoic rocks as far as Stadbergen on the Diemel. In this we have 

 a close approximation to an old coast line : in a direction at right 

 angles to this line the detrital beds thin away and become finer ; 

 and from west to east the alternations of coarse materials with fine 

 sedimentary matter are more frequently repeated. A like change in 

 the arenaceous band dividing the Planer, would seem to show that 

 the present bay-like form of the cretaceous map of Westphalia is 

 due to the form assumed by certain lines of disturbed strata, at 

 some pre-cretaceous period. Along the whole of this line the 

 conditions of accumulation are just such as the Tourtia of 

 Belgium presents, of which according to Mr Roemer it is the exact 

 equivalent. If this was ever made matter of doubt owing to the 

 copious marine fauna of the sands of Essen, the difficulty is re- 

 moved by an examination of the group further east. It is then 

 seen that the assemblage about Essen was due to local con- 

 ditions, whilst about Bilmerich, with sections which strikingly re- 

 semble those of Tournay, the beds contain Area cardiaeformis, and 

 the large Pleurostimaria of that locality. 



Mr Roemer give a list of 104 species from Essen. Of these we 

 recognise as British, Scyphia infundibuliformis (Farr.), S. fur- 

 cata (Farr.), Manon, peziza (Farr.), Tragos pulvinarium (Farr.), 

 Micrabacea coronula (Worm.), Cidaris vesiculosa (u. ch.), Diadema 

 ornatum (u. gr. s. 1. ch.), Goniopygus peltatus (u. gr. s.), Cerato- 

 mus rostratus (Worm.), Discoidea subuculus (Worm., 1. ch.) Cato- 

 pygus carinatus (Worm. 1. ch.), Nucleolites lacunosus (u. gr. s.), N. 

 cordatus (u. gr. s.) Terebratula latissima (Farr. to 1. ch.), T. nuci- 

 formis (Farr.), T. oblonga (Beaumont), T. nerviensis (Farr.), Ostrea 

 macroptera (0. diluv.), O. carinata (u. gr. s.), Exogyra halotoidea 

 Worm. Blackdn.), E. conica (greensands of the West of England), 

 E. plicatula, Pecten asper (Worm. Blackdn.), P. cretosus (w. ch.), 

 P. laminosus (1. ch.), P. costatus, Spondylus striatus (u. gr, s. 

 Wilts), Nautilus elegans (1. ch.), N. simplex (n. grs. s.), Ammon- 

 ites varians (u. gr. s.), A. peramplus (1. ch.), A. Mantelli (u. gr. s.), 

 Turrilites costatus (1. ch.) 



The inference as to the relative age of the sands of Essen is that, 

 considered according to the British cretaceous series they are the 

 equivalents of the chalk marl, and of the sands which are beneath 

 it ; as those of Warminster. 



It will be thus seen that round the great cretaceous bay of West- 

 phalia there is a line of littoral sea beds, surmounted by deep-sea ac- 

 cumulations of vast thickness, such as the Planer marls and lime- 

 stones ; the continuity of which conditions seems to have been more 

 than once disturbed by oscillations such as caused the outspread 

 of the coarse bands which are subordinate to that great group. 



