334: FLORA OF UPPEE CRETACEOUS PERIOD. [Oh. XYII. 



the Proteacese, of which there are between sixty and seventy species, 

 many of extinct genera, but some referred to the following living forms 

 — Dryandra, Grevillea, Hakea, Banksia, Persoonia — all now belonging 

 to Australia, and Leucospermum, species of which form small bushes 

 at the Cape. 



The epidermis of the leaves of many of these Aix plants, especially 

 of the Proteacese, is so perfectly preserved in an envelope of fine clay 

 that under the microscope the stomata, or polygonal cellules, can be 

 detected, and their peculiar arrangement is identical with that known 

 to characterize some living Proteacese (Grevillea, for example). An oc- 

 casional admixture of Fucoids and Zosterites attests, like the shells, 

 the presence of saltwater. 



Of insects Dr. Debey has obtained about ten species of the families 

 Curculionidse and Carabidse. 



The, age of the beds containing this remarkable assemblage of 

 plants was for a long time matter of dispute. They were at first 

 erroneously referred to the Middle Tertiary, and afterwards to the 

 Lower Cretaceous series, but they are in truth the equivalents of the 

 white chalk and Chalk Marl, or Senonien of D'Orbigny. Such was 

 Ferdinand Romer's opinion in 1853,* and after examining the coun- 

 try in 1857, I satisfied myself that he was right, although the white 

 siliceous sands of the lower beds, and the green grains in the upper 

 part of the formation, caused it to differ in mineral character from our 

 white chalk. 



In travelling from Maestricht to Aix-la-Chapelle, we first pass 

 from the Maestricht beds to white chalk, with flints, about 300 feet 

 thick, next to which, in descending order, we find chalk without flints, 

 and Chalk Marl; and below this again, greensand, which contains 

 Belemnitella mucronata (fig. 290, p. 325), and other fossils, showing 

 that it is not the equivalent of the English Upper Greensand. Below 

 this are the white and yellow sands of Aix, about 400 feet thick, which 

 rest immediately on ancient Devonian rocks, highly inclined. Some of 

 the sand in the lower beds has concreted into solid masses of sandstone, 

 like the German Quader Sandstein. 



Beds of fine clay, with fossil plants, and with seams of lignite and 

 even perfect coal, are intercalated. Floating wood, containing perfo- 

 rating shells, such as Pholas, and Gastrochoena also occur. There are 

 likewise a few beds of a yellowish brown limestone, with marine shells, 

 which enable us to identify the lowest with the highest plant-beds. 

 Among these shells are Pecten quadricostatus, and several others which 

 are common to the upper and lower part of the series, and a Trigonia, 

 called by some of the Aix naturalists T. alacformis, which, as M. Bos- 

 quet pointed out to me, agrees far better in character with D'Grbigny's 

 T. limbata, a shell of the white chalk. ' On the whole the organic re- 



* F. Romer, Kreidebildung der Gegend von Aachen. Deutsch. Geol. Gesellsch. 

 vii. 534. 







