32 THE FLORA OF THE AMBOY CLAYS. 
of our New Jersey plants in the Cretaceous beds of Aachen. ‘The flora of 
the Aachen clays has never been fully described. Debey and Ettings- 
hausen began to illustrate it, and published two parts of a proposed 
monograph. These included Thallophytes and ferns, but the conifers, 
cyeads, and angiosperms were left untouched; at least, though partially 
studied, they were not figured or described. To make the comparison 
which it was impossible to do through books, I at one time took occasion 
to go to Aachen, and had the privilege of examining a very considerable 
portion of the collections made by Dr. Debey. I found that the formation 
there resembles our Amboy Clays very much lithologically, and some of 
the strata are of economic importance and have been extensively worked. 
Unfortunately, the spread of the town has covered most of the pits where 
excavations were made, and hereafter it will be impossible to enjoy the 
opportunity possessed by Dr. Debey, who for twenty-five years was a 
practicing physician in Aachen and had in his pay the men employed in 
the clay pits, so that the collections he made were very large. These have 
since been made up into sets and sold. 
In the few hours I spent in the examination of Dr. Debey’s plants it 
was impossible for me to make the systematic comparison with the Amboy 
flora that is desirable, but that will doubtless be made in time, when some- 
one takes up the work begun by Dr. Debey and gives a full description of 
the plants he found. I was greatly interested to see the general corre- 
spondence in the character of the floras, and to identify with certainty such 
plants as Moriconia cyclotoron, Cunninghamites elegans, Asplenium Foerster, ete. 
The number of identical species will undoubtedly be largely augmented, 
and there can be no mistake about the parallelism of the two formations. 
Dr. Charles Horion, of Liege, has given a lucid explanation of the 
structure and relations of the Aachen beds in his Notice sur le Terrain 
Crétacé de la Belgique (Bulletin de la Société Géologique de France, 2™° 
Série, Vol. XVI, p. 635), and has shown that the formation of that region 
covers the upper half of the Cretaceous system, the upper member being 
the Maestricht beds, which is the summit of the system, while the beds at 
Aachen, though all mechanical—clay, sands, etc.—range down to about its 
middle, or form the equivalent of the Upper Greensand of England. 
