March 29, 1895.] 



SCIENCE. 



341 



our James River series. An important 

 plant bearing locality between JIatta and 

 Valle-de-Lobos is regarded as Yalanginian 

 or Xeocomian. It may be compared with 

 the Fredericksbiirg l)eds of the Potomac 

 formation. The beds of Ahnargem, which 

 have furnished many species, overlie the 

 recognized Urgonian and probabl}' belong 

 to the upper portion of that subdivision, 

 or possibly to the base of the next 

 one called by the French geologists the 

 Aptian. It corresponds quite closely with 

 the Konie beds of Greenland and may be 

 compared with the jMount Vernon clays of 

 the Potomac formation, though it is probably 

 higher. Then there is a series of beds in 

 the vicinitj- of Torres- Yedras, viz., at S. 

 Sebastiao, Quinta-da-Fonte-Nova, Forca, 

 Quinta-do-Chafariz, Portella-da- Villa, etc., 

 and another series in the vicinitj' of Cereal 

 and Zambujeiro, wliich are classed as Aptian, 

 between which and the last named there is 

 a considerable interval, including marine 

 deposits belonging to the Urgonian. Cer- 

 tain other beds, as at Calxaria and Caran- 

 guejeira, are less definitely fixed geologic- 

 ally, but probably belong to about the same 

 horizon. The Aptian of the French geolo- 

 gists lies between the Urgonian below and 

 the Albian above, and corresponds in the 

 main with the lower Greensand of England. 

 It may be compared with those deposits of 

 the Potomac formation near Aquia Creek 

 called the Brooke beds by Professor Fon- 

 taine, which have yielded a large number of 

 fossil plants, including such well-marked 

 dicotyledons as Celastrophyllum and Sapin- 

 dophyllum. 



Above these beds there is an abundant 

 plant localitj' at Buarcos, which is classed 

 as Albian, and still higher othei-s at Naza- 

 reth, Alcancde and Monsanto, also regarded 

 as Albian, but as belonging to that upper- 

 most member called \'raconiuan. The Al- 

 bian corresponds in a general waj' with the 

 Gault and is the uppermost section of the 



Lower Cretaceous, the overlying beds being 

 Cenomanian, which is the lowest subdivision 

 of the I'pper Cretaceous. These Albian 

 plant bearing beds may be roughlj' compared 

 with what has been called in America the 

 Amboy clays, but which has recently been 

 more correctly named by Professor William 

 B. Clark the Raritaii formation. In Amer- 

 ica, as in Portugal, this deposit maj^ also be 

 divided into two parts, a lower and an upper, 

 the former consisting of the beds along the 

 Raritan, which themselves have a consider- 

 able thickness and show marked changes in 

 the Hora, while to the latter belong the de- 

 posits on Staten Island, Long Island and 

 Martha's Vineyard, which have yielded 

 large collections chiefly from indurated no- 

 dules formed in red claj*. 



Finally', in the Valley of Alcantara, at 

 Padro, Pombal and Villa-'N'erde-de-Tentu- 

 gal, there are plant Ijearing beds belonging 

 to the Cenomanian. It is possible that these 

 latter may not be higher than those of Long 

 Island and Gay Head. 



The floras of the several horizons in the 

 Lower Cretaceous of Portugal differ less in 

 their abundance than those of the Jurassic; 

 the largest is that of the Valanginiau, 

 amounting to 86 species or over -13 per cent. ; 

 the Urgonian has yielded only 2.5 species or 

 12 per cent., the Aptian 42 species or a little 

 more than 21 per cent., the Lower Albian 

 58 species or over 25 per cent., and the Up- 

 per Albian or Vracounian 28 species or 14 

 per cent. The striking coincidence of the 

 parallelism between these horizons and those 

 of the Potomac formation in America is still 

 further heightened by the circumstance, ac- 

 cidental perhaps, that the numerical pro- 

 portion existing between the species now 

 known at the corresponding horizons in 

 America is very nearly the same. The Basal 

 Potomac, corresponding to the Vraconnian, 

 has yielded 329 species or a little over 44 

 percent.; the Mount Vernon clays, which 

 were compared with the Urgonian, 42 species 



