PROSSER. | Cretaceous.—The Dakota Sandstone. 194 
Professor Cope also described the remains of a crocodile, Hypo- 
saurus vebbii, which was found in a bluish stratum in digging a well 
at Brookville, Saline county.1 The age of the formation was in- 
correctly given as the Benton; it is either the Wellington or Mentor 
and probably the latter as it was referred by Professor Mudge to 
the Dakota.” 
Tt is a well known fact that the dicotyledonous leaf-bearing part 
of the Dakota is referred to the Upper Cretaceous and usually re- 
garded as forming its lowest subdivision. In 1874 Professor Les- 
quereux stated that the Dakota group corresponded “to the Upper 
Cretaceous of Europe’! which he correlated more precisely in 1883 
when he said that ‘The flora of the Dakota group * * * is con- 
sidered as relating the formation which it represents to the Ceno- 
manian or Middle Cretaceous.’ This conclusion was apparently 
unchanged in his final monograph on “The Flora of the Dakota 
Group” published after his death.® 
As has already been mentioned some of the Dakota fossil leaves 
occur either at the same, or nearly the same, horizon as the Mentor 
fossil shells. This agrees with the observations of Professor 
Mudge who was the first extensive collector of both fossil shells 
and leaves in the Kansas Dakota. Professor Lesquereux was aware 
of this association of the plants and marine mollusks for in support 
of his belief that the Dakota was a marine formation he quoted 
the following statement of Professor Mudge: “They [the marine 
shells] are in the same strata and in the vicinity of several deposits 
with the dicotyledonous leaves,and together with the plants, identify 
this portion of the sandstone as belonging to the Dakota group of 
the Cretaceous.”’ The supposition that a part of the Dakota flora of 
1 Fifth Annual Report U. 8S. Geological Survey of Montana and Territories, 1872, 
p. 327. Also in Report U. S. Geological Survey Territories, Hayden, Vol. II,— 
Vertebrata of the Cretaceous Formations—1875, pp. 17, 67, 68. 
2 Ninth Annual Report U. S. Geological and Geographical Survey Territories, 
Hayden, 1877, p. 291. 
3 Bulletin U. S. Geological Survey, No. 82; Correlation Papers—Cretaceous—1891, 
p. 158; where Dr. White gives the classification of the Upper Cretaceous. 
Re caie U. S. Geological Survey Territories, Vol. VI,—The Cretaceous Flora 
10); Akay, 
5 Ibid., Vol. Vifl,--The Cretaceous and Tertiary Floras—p. 92. 
6 Mon. U. S. Geological Survey, 1892, Vol. XVII; see p. 20 where the age of the 
Dakota group is considered. 
7 Report U. S. Geological Survey Territories, Vol. VI, p. 26. The above quotation 
was published by Professor Mudge in a description of the ‘“‘Red sandstone of Central 
Kansas” in Trans. Kans. Acad. Sci., Vol. I, 1873 (?) reprint 1896, p. 39. 
