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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. 3 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 JVatica, 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 Neocomian 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 

 seen alternating with beds of clay and lignite, all of which are upheaved 

 and much distorted. It was found impossible to devote to the examina- 

 tion of these formations time enough to determine their relations to the 

 Cretaceous and Tertiary strata of this region, without running the risk of 

 being cut off from the party and murdered by the Indians. Amongst a 

 few fossils that were collected here, however, Prof. Leidy finds teeth 

 which he refers to two or three genera of large Saurians allied to the 

 Iguanodon, Megalosaurus, &c. There are also in the collection from 

 some of these beds, one or two species of Unto, one or more of Cyclas 

 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. 



We 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 fossils in these beds, but were at that time impressed 

 with the opinion that they belonged to the lower part of No. 1, which is 

 well exposed a little higher up the river at the mouth of the Big Sioux, 

 but soon dips beneath the water level to be seen no more between there 

 and the far distant point already mentioned, near the mouth of Muscle- 

 shell river.* 



[Here follow descriptions of species : From Fort Union, Paludina Leai ; 

 — From three miles above Fort Union, Cyclas formosa, C. fragilis, C. sub- 

 ellipticus, Pupa helicoides, Physa longiuscula, P. rhomboidea. — Three 

 miles below Fort Union, Bulimus? teres, B. ? vermiculus, Limnsea tenui- 

 costa, Physa Nebrascensis, Planorbis umbilicatus, Velletia (Ancylus) 

 minuta, Paludina retusa, Valvata parvula, Melania minutula. — Ten miles 

 below Fort Union, Paludina trochiformis, P. Leidyi. — Ten miles above 

 Fort Union, Melania multistriata, M. Nebrascensis. — Near Moreau river, 

 with bones of Titanotherium ? Cyrena Moreauensis, C. intermedia. — Bad 

 Lands of the Judith, Cyrena occidentalis, Physa subelongata, Paludina 

 vetula, P. Conradi, Melania convexa. — Mouth of the Judith, associated 



* The foregoing remarks are based upon the observations and collections of Dr. 

 Hayden. 



