290 Organic Remains of the 
whole that Dr. Morton’s inference seems in a great measure estab- 
lished. How far the cretaceous group of the United States may be 
separated beneath and above, from other deposits more or less con- 
temporaneous with those of Europe, remains an interesting problem 
which it is hoped American geologists will endeavor to solve-—As- 
suming that the American ferruginous sand formation belongs to this 
[cretaceous] group, of which there seems great probability, it would 
appear that the great white carbonate of lime deposit, or chalk, did 
not extend there ; but that a series of sands, clays and gravels con- 
stituted the whole group.” ath 
In reference to the preceding passages, I may briefly observe, that 
the whole super-cretaceous group, or tertiary series, (excepting only 
the fresh water deposits) is now satisfactorily identified in this coun- 
try. Thus we have the upper, middle and lower tertiary forma- 
tions,* all based directly or indirectly on the ferruginous sand; and 
I may repeat, that so far as my observations have extended, not a 
solitary fossil of the latter formation has been detected in the super- 
posed strata. ‘% 
Tn resuming the subject of organic remains it may be observed, 
that I_have figured on the present occasion, some of the most re- 
markable species only, the remaining illustrations being reserved for 
a separate edition of this Synopsis: for the same reason the plates 
here given do not follow each other in numerical order. | 
ORGANIC REMAINS. 
CHAMBERED UNIVALVES. 
AMMONITES. . 
A. telifer. (S.G.M.) A remarkable species, of which I possess 
several fragments from the Delaware marl, almost too imperfect for 
description, and yet so different from the other species as to induce 
me to give itaname. It wilF be figured in the second edition of 
I take this occasion to remark that the J. hippocrepis of DeKay, 
inserted in the first part of this Synopsis, is merely a transverse section 
of Scaphites Cuvier’. This formation, therefore, possesses but four 
published species of Ammonites, viz. 2. placenta, A. Delawarensis, 
A. Vanuremi and A. telifer. seh : se ; 
* I take the liberty (for reasons to be given in another place) of substituting these 
names for those of Upper marine, London clay and Plastic clay formations. 
