462 F. B. Meek—Age of the Lignitic formation, ete. 
From the foregoing remarks it will be seen that our present 
information in regard to the age of the Bitter Creek series may be 
summarily stated as follows: 
1. That it is conformable to an extensive fresh-water Terti 
formation above, from which it does not differ materially in litho- 
logical characters, excepting in containing numerous beds an 
seams of coal. 
2 at it seems also to be conformable to a somewhat differ. 
ntly composed group of strata (1,000 feet, or possibly much more 
in thickness) below, apparently containing little if any coal, and 
believed to be of Cretaceous age. 
3. That it shows no essential difference of lithological charac- 
ters from the Cretaceous coal-bearing rocks at Bear River and 
oalville. 
Cretaceous fossils, at Coalville, in é : 
5. That all of its animal remains yet known are specifically dif- 
ferent from any of those hitherto found in any of the other forma- 
tions of this region, or, with perhaps two, or possibly three excep- 
tions, elsewhere. 
6. That all of its known invertebrate remains are mollusks, 
consisting of about thirteen species and varieties of marine, brack- 
ish, and fresh-water types, none of which belong to genera peculiar 
to the Cretaceous or any older rocks, but all to such genera as are 
ike common to the Cretaceous, Tertiary, and present epochs, with 
same the exception of Goniobasis (which is not yet certainly 
own from the Cretaceous). 
7. That, on the one hand, two or three of its species belong to 
sections or subgenera (Zeptesthes and Veloritina) apparently 
characteristic of the Eocene Tertiary of Europe, and are even very 
while a Viviparus, found in one of the upper beds, is almost cer 
tainly identical with the V. trochiformis of the fresh-water Lig- 
nite formation of the r Missouri; a formation that has 
a large reptilian (occurring in ct association with the Vivr- 
parus mentioned above), which, accor Professor Cope, 
is a decidedly Cretaceous type, ing, as he states, a huge Dino- 
saurian. 
