428 Scientific Intelligence. 
river, a lower rock, a sandstone, rises above the-water level. This is prob- 
ably No. 1 of the series, No. 2 and No. 8 not being represented here, It 
is worthy of note that out of two species of Mactra, two of Tellina, two 
of Inoceramus, one of Pholadomya, two of Natica, and one Baculite, 
found in this rock, not one is known to occur in any of the higher forma- 
tions, and some of these species are not unlike Weocomian forms. 
In consequence of the increasing inclination of the strata, this last men- 
_ tioned sandstone rises in the vicinity of North Mountain river as much as 
250 feet above the Missouri. Here, or near this, begins a wild and deso- 
late region, known as the Mauvaises Terres or Bad Lands of the Judith. 
At various places in these Bad Lands a sandstone similar to No. 1 was 
some of these beds, one or two species of Unio, one or more of Cycias 
or Cyrena, and a few crushed specimens of Gasteropoda like Paludina 
and Melania. From these facts, we are strongly inclined to think with 
Prof. Leidy, that there may be here, at the base of the Cretaceous system, 
a fresh-water formation like the Wealden. Inasmuch, however, as there 
certainly are some outliers of fresh-water Tertiary in these Bad Lands, we 
would suggest that it is barely possible these remains may belong to that 
epoch, though the shells appear to be all distinct species from those found 
in the Tertiary at all the other localities in this region. 
e remember seeing in 1853, between the mouth of Big Sioux and 
Platte rivers on the Missouri, some exposures very similar to those of the 
Bad Lands of the Judith, excepting that there appeared to be no beds of 
Lignite. We saw no ossils in these beds, but were at that time impr 
with the opinion that they belonged to the lower part of No. 1, which is 
nse follow descriptions of species: From Fort Union, Paludina Leai} 
pees C. fragilis, C. sub- 
re 
nion, Bulimus? teres, B.? vermicul mna tenui- 
2 ulus, Li 
costa, Physa Nebrascensis, Planorbis umbilicatus, Velletia (Ancylt ) 
minuta, Paludina retusa, Valvata parvula, Melania minutula.—Zen miles 
" i foregoing remarks are based upon the observations and collections of Dr. 
