12 AMERICAN GEOLOGY. I am much inclined to adopt the opinion of Prof. Heer, and 1 suspect that your Lower Cretaceous N° 1 of the mouth of Judith river is partly Jurassic and partly Miocene; the Baculites found with the leaves being probably a cretaceous Baculites of the neighboring strata that has been washed away from the cliff during the deposi tion of the Tertiary rocks. To continue, I also regard your Black Hill Lower Cretaceous N° 1 with dicotyledonous leaves as Miocene as well as the similar formation indicated some where in Kansas by Major Hawn. Further, after a careful exa mination, Prof. Heer thinks that the deposit in the vicinity of Fort Bent, from which Lieut. Abert obtained leaves, is also Lower Miocene and equivalent to your formation of the Big Sioux river; and that the Muddy river coal discovered by Col. Fre mont is of Tertiary age instead of Jurassic as it was pronounced by James Hall. The fossil leaves figured by Prof. Bailey in Abert’s Report (see: Beport of Lieut. J. W. Abert, of his exa mination of New Mexico, in the year 1846 — 47) belong to two species, the lanceolate leaf is identical with your Laurus pri- migenia of the Big Sioux, and the large cordate leaf is a spe cies of Ficus; a Tertiary genus still living. But 1 will remark that Abert says p. 523 of his Report, that he did not find those leaves himself at the Raton mountain; he examined the coal, but was unable to find a single impression of leaves, and the specimens figured were given to him at Fort Bent by hunters, so the exact place of the leaves is doubtful; they may come from other strata of the vicinity of Fort Bent. I say this because I suspect the bituminous coal from the Raton to be the equivalent of the coal I found at Ojo Pescado near Zuni which is of Jurassic age. James Hall says: « Glossopteris Phil- «lipsii? Brong. I have referred this species to the G. Phillipsii, «as being the only description and figure accessible to me, to «which this fossil bears any near resemblance. The geologi cal position of that fossil is so well ascertained to be the « schists of the upper part of the oolitic period, that, relying «upon the evidence offered by a single species, we might re- « gard it as a strong argument for referring all the other spe-