426 GEOLOGICAL SURVEY OF THE TEERITOKIES. 



This species, like the former, are referable to the genus Credneria, one 

 species of which, Credneria Leconteana, Lsqx., is related to this. The 

 description of Credneria Leconteana, as given in Amer. Jour. Sci. 

 and Arts, July, 1868, p. 98, answers exactly the description and 

 figure of Credneria macrophylla, Heer, in Mol. Fl., p. 16, PI. 4. Only 

 one of the basilar veinlets is marked on my figure of this species, rep- 

 resenting our best, though incomplete, specimen ; but the descrip- 

 tion remarks the position of two lower secondary pai7's of nerves, as 

 observed from other specimens, and which indicate the essential character 

 of the leaves of the genus Credneria. — Fort Harker. 



PTEROSPEEivnTES Haydenii, Lsqx., llept. 1871, p. 302. 



A good specimen of this species has been found at Fort Harker. It 

 answers in every point the description of this species, loc. cit. 



Pterospeemites Euaosus, sp. nov. 



Leaves rather small, coriaceous, rough and wrinkled on the surface, 

 triangular oblong in outline, truncate obtuse to the base, obtusely 

 pointed, medial nerve very thick, overlapped at its base by the undulate 

 borders. 



The leaves vary, at least in our specimens, from 9 to 12 cent, long 

 and 6 to 9 cent, broad. The nervation is that of the genus, three pairs 

 of thinner basilar veins passing horizontally, or in a downward direc- 

 tion, to the borders. The secondary veins above are thick, emerging at 

 an open angle of divergence from the medial nerve, branching outside 

 and curving upward in ascending to the point of an obtuse lobe, or the 

 enlarged middle of the leaves. The strong nervilles, deeply impressed 

 into the stone, give to the leaves of this species a peculiar ajjpearance. — 

 Salina Valley. 



CONCLUSION. 



From this enumeration of Cretaceous fossil-plants, it appears that in 

 the twenty-three mentioned species, fourteen are considered as new ; 

 three as identical with some ones already described from Europe, but 

 not as yet discovered in our Cretaceous strata; and six have been for- 

 metly described from the same Dakota group. It is thus an addition 

 of seventeen species to the American Cretaceous flora, which now has 

 about one hundred and twenty so-called species. 



The remarks made in the first part of this paper, in regard to the 

 analogy of some vegetable forms of our Cretaceous with those of plants 

 of our time, and also of the Miocene flora of Europe, are rather con- 

 firmed than eliminated by the descriptions of these species. They rep- 

 resent especially forms of Sassafras, Pterospermites, Fopulites, with Seq- 

 uoia Beichenhachi, two ferns, &g. Considering the relation of the Cre- 

 taceous groui:)S, enough has been said already in this and in the former 

 report. I wish only to record once more the geological evidence afforded 

 by the remarkable disconnection of the American Cretaceous flora from 

 that of the Eocene. Both these formations are now represented by a num- 

 ber of species large enough for a reliable comparison, which, made by any 

 palaeontologist, proves that there is not a single species, either identical 

 or in intimate relation, in both the Cretaceous and the Eocene flora of our 

 continent. Even that fucoidal plant described as Fucoides digitatus, is 

 not related whatever to any of the marine species described from the 



