41 



horizon of thin seams of coal. However this may be, I can assert, in 

 the most positive manner, that the beds from which these fossils came^ 

 are clearly, and beyond all question, of Cretaceous age. This is not only 

 shown by the presence, among the fossils found in them, of the well- 

 known and widely-distributed Cretaceous genus and species Ammonites 

 lohatits, Tuomey,* but even more clearly by the fact that all of the other 

 identified species of bivalves and univalves are certainly identical with 

 species widely distributed in the Upper Missouri country in beds con- 

 taining numerous examples of Ammonites, iScapliites, Baculites, Inocera- 

 mus, and other decided Cretaceous types. 



At the same time that all of the identified molluscan remains from 

 these beds are such decided Cretaceous types, it will be observed that 

 a number of specimens, which I am entirely unable to distinguish from 

 a fucoid referred, by Professor Lesquereux, to the genus Salymenites, 

 and widely distributed in the Brown-coal deposits of the far-west, also 

 occur here directly associated with these Cretaceous shells. This fucoid 

 has been considered a Tertiary type by my able and distinguished friend, 

 Professor Lesquereux, and relied upon as at least one of the evidences 

 that these Brown-coal deposits belong to the Tertiary epoch, and not to 

 the Cretaceous. It seems to me evident, however, from the occurrence 

 of this fossil here, along with numerous decidedly Cretaceous shells, as 

 well as at Coalville in Utah, where I found it at least 1,000 feet below 

 the horizon of well-marked Cretaceous strata, that if, at least, can no 

 longer be regarded as an exclusively Tertiary type. 



I should not omit to state here, bowever, that Mr. Holmes, who col- 

 lected most of the fossils under consideration, informed me that he did 

 not find, in the beds from which they were obtained, any of the dicoty- 

 ledonous leaves so numerous in the coal-strata very widely distributed 

 in Wyoming, Colorado, and other parts of the far- west. This is also 

 precisely the case at Coalville, Utah, where I found tbis fucoid ranging 

 far down below well-'defined Cretaceous strata ; while a two-weeks' 

 careful search there by Doctor Bannister and myself failed to discover 

 any of these dicotyledonous leaves so common, along with this same 

 fucoid, at Black Butte, and other localities in Wyoming, as well as in 

 Colorado. 



It should also be noticed that not a single species of these animal re- 

 mains (which are very abundant in individuals at the Colorado localities 

 under consideration) can be identified with an^^ of the forms yet known 

 from the coal-bearing strata of that region, or from Wyoming and other 

 localities farther w^estward. 



The specimens from farther eastward were taken from a shaft sunk 

 on the Kansas Pacific Railroad, at a locality about two hundred miles 

 east of Denver, Col. I have seen no section of the strata penetrated by 

 this shaft, but have been informed that it was sunk to a depth of 1,200 

 feet, and that it passed through many beds of sandstone and some shale 

 and brown coal. The specimens submitted to me were found at two 

 different horizons: one about 400 feet below the surface; and the other 

 at a depth of about 45 feet. Whether or not any of the other beds 

 struck contained fossils, I have not been informed. Those from the 

 lower horizon are contained in a rather firm, dark shale, said to overlie 



* I am now almost entirely satisfied that this species is identical with au Upper- 

 chalk form of Limbonrg, that has been identified by Binkhorst with Ammonites Peder- 

 nalis, von Bucb. (See Mong. Gast. et des Cephalop. de la Craie snp. du Duche de 

 Limbonrg, 21, pi. V^, figs. 6 a, i, &c.). I have not at hand von Buch's figures and 

 description of his species, bnt the shell figured by Binkhorst is apparently not distinct 

 from that before me ; though I doubt its identity with the Texas shell figured by 

 Roemer under von Buch's name. 



