406 Notices of Memoirs — Vanclen Broeck's Geology of Antwerp. 



percolation of water giving rise to great irregularity of alteration, and 

 producing the appearance, often strongly marked, of unconformity. 

 To separate such deposits by their colour, therefore, is to mass all 

 altered beds as of one age, all unaltered as of another, leading of 

 course to hopeless confusion in lists of fossils based on this division, 

 and this confusion has been increased by the inclusion of specimens 

 from post-Tertiary deposits of similar lithological character. All lists 

 hitherto published are therefore to a large extent worthless, with the 

 exception of those recently compiled by M. Cogels. 



The Middle Sands are rather Diestian than Scaldesian in their 

 faunal affinities, and slightly anterior to the Coralline Crag, to which 

 they are closely allied. By the northward and westward movement 

 of the area of deposition, due to the elevation of Belgium and 

 simultaneous depression of Holland and East Anglia, the Coralline 

 Crag was still in process of deposition when the Belgian area 

 emerged. 



The Middle Sands have two facies, one of comparatively shallow 

 water, distinguished by the predominance of Isocardia cor, the other 

 of deeper water, notable for its profusion of Bryozoa. Enormous 

 quantities of Cetacean bones, often as entire skeletons and connected 

 vertebral columns, occur throughout the series, but the Ziphioids 

 and Delphinidas of the Lower Sands are here replaced by Mysticeti 

 and Phocidae. The fish are mostly Selachians, some of them of 

 enormous bulk.' 



Like the Coralline Crag, the Middle Sands have suffered great 

 denudation previous to the deposition of the Upper Sands (=Red 

 Crag). 



Eemarks on the horizon of certain local deposits and of Terebratula 

 grandis (a Middle Sands species referred by M, Cogels, from deficient 

 evidence, to the Lower Sands) are followed by a sketch of the 

 geography of the Middle Sand period. The Belgian basin extended 

 Irom Cotentin to Denmark and Iceland : the Mediterranean had 

 nearly its present outline, whilst in Austria and South Russia occur 

 isolated marine deposits of this age. 



Passing to the Upper Sands we find a number of synonyms of 

 which but one need be named, Sables a Trophon antiquum, given by 

 M. Cogels in 1874. 



The Upper Sands are of littoral origin, coarse and pebbly, rarely 

 more than 14 feet thick, grey where protected by overlying im- 

 permeable beds from pei'colating water, but mostly oxidised. Their 

 derived fossils being clearly distinguishable from contemporaneous 

 species, these Antwerp beds may help to settle the vexed question of 

 " derivation " in the English Eed Crag, as many species from the 

 latter, supposed to be derived, are found in the Upper Sands. 



As with the previous series, the Upper Sands are slightly anterior 

 to the Red Crag, except perhaps the Crag of Walton-on-the-Naze, 

 which has an earlier facies than the rest of the Eed Crag, and may be 

 synchronous with the Upper Sands. The base of both contains 



^ Garcliarodon megalodon was 70 feet long, and its jaws were 14 feet in cii'cum- 

 ference. 



