68 Scientific Intelligence. 
have been identified—I do not presume to say upon what authority. 
With some of the latter your specimens are intimately reiated, 
perhaps identical. You have two or three fragments of teeth (one 
nearly perfect), which agen! belong to the same genus as those 
from the sey Greensand and later deposits known as 
Saurocephalus. All these tedth evidently belong to a later epoch 
than the chalky beds on the Big Sioux river, near Sioux City, the 
fishes of which have a much stronger resemblance to those from 
the Chalk of Europe than have the specimens under consideration, 
while the squaloid teeth ahs the latter bear the most intimate 
resemblance to certain forms o saeseaden from the Cretaceous rocks 
= Alabama. Hence I conclude your specimens have been derived 
om deposits of the Later Drevetedin, probably squivatons to the 
‘Alsbarn a fish-bearing Cretaceous st rata. That they are very late 
Pickasated forms there can be no doubt, from the fact of their 
close ‘elationship to teeth found in the Eocene of the Old World. 
Iam not prepared to show how close this relationship is, although 
the first sig t of your little collection strongly suggested their 
Eocene age.” 
Although all = specimens forming the subject of this memoir 
have been found in the drift, they have been found at such local- 
pee and under such circumstances as to leave no doubt in the 
ind of the writer that the Cretaceous sea once extended as far 
pane between the 42d and 44th parallels of latitude, as the 
92d degree of longitude west from Greenwich. This is nearly two 
hundred miles further eastward than any Cretaceous deposits were 
ever known to have extended in the interior region of North 
America at the time I commenced my official examination of the 
geology of Iowa in 1866. What gives additional interest to these 
discoveries is the fact that the fossils doubtless belong to a Meso- 
zoic epoch as late as any yet oo in any part of North 
erica, and much later than that any Cretaceous strata of 
other strata is doand is in Here ihr Misacabes: where the Inoce- 
mus beds, as before stated, rest upon the Azoic rocks, the older 
Puehaabouns sandstone being absent there, but present about 
150 miles to the southwestward. 
None of the strata in which these fossils were originally depos- 
ited have, as before intimated, been found in situ, but fragments 
of them, and also the material of the drift to which ar evidently, 
in part, gave jie pasts that they were soft and friable like most 
of the Cretaceous rocks of the great interior region. Conse- 
quently they were oni disturbed and removed by the forces in 
— during the Glacial epoch. While much of the material 
these strata was doubtless transported to great distances and its 
character as such thus obliterated, delicate fossils, as well as soft 
and friable fragments of the strata, are found embedded in the 
