446 SCIENCE PROGRESS. 



by clays with Lima altemicosta. Sandstones alternate 

 with these clays and in the succeeding beds become pre- 

 dominant. They extend up to, and include the repre- 

 sentatives of the Portlandian. 



South of the Tagus nearly the whole of the Malm, and 

 indeed nearly the whole of the Jurassic, consists of lime- 

 stones, dolomites and marly limestones, excepting in the 

 uppermost part, where coarse conglomerates are sometimes 

 found (9). But the various localities show very different 

 developments. In the eastern part of Algarve the series 

 is complete, but towards the west there are very consider- 

 able gaps in the succession. In Western Algarve and at 

 Carrapateira the lower part of the Lusitanian is absent. 

 During the Jurassic period, therefore, Eastern Algarve lay 

 under moderately deep water throughout, while the rest of 

 Portugal, with its shallow water and lignite deposits and its 

 interrupted sequences, seems during the deposition of the 

 Malm to have been in great part land and in part covered 

 only by shallow water. Portugal in fact is an exception to 

 the general rule which obtains through most of Europe, 

 that the close of the Lias period was marked by a great 

 extension of the ocean. Throughout Portugal the Lias is 

 entirely marine ; while the Malm is generally in part absent 

 and in part shows numerous brackish and lacustrine de- 

 posits (40). 



Cretaceous. — The Cretaceous deposits occupy even a 

 smaller space than the Jurassic. They cover, however, a 

 good deal of ground immediately north of Lisbon ; and 

 several patches are found within the Mesozoic area farther 

 north ; while Cretaceous beds are also known in the 

 littoral region of Algarve. 



Again M. Choffat is our chief authority. He has de- 

 scribed in some detail the Cretaceous of Cintra, Bellas, and 

 Lisbon (extending from Cabo da Roca to the Tagus) (4) ; 

 the Cretaceous patches of Torres Vedras, Peniche, and 

 Cereal farther north (11); and also the Cretaceous band in 

 Algarve (9). As in the Cretaceous of Southern Europe 

 generally, Rudistae are among the characteristic fossils, 

 although the genus Hippurites itself appears to be absent. 



