150 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
Shumardi sp. nov., adding the following “Observations”:—“This 
species differs from all the Cretaceous Ammonites hitherto described; 
it resembles slightly the Am. coronatus of the Oxfordian, but is dis¬ 
tinguished by its two lines of tubercles and its keeled back” This 
remark is important, as will be seen further on. 
In October, 1887, Mr. R. T. Hill, in a paper entitled Texas sec¬ 
tion of American Cretaceous (Amer. journ. sc., vol. 34, p. 305-306), 
says : “ The basal, or Dinosaur sands of my section, which are inter¬ 
polated between the Fredericksburg division and the undoubted 
Carboniferous, are the shore detritus of the Mesozoic sea when it 
bordered upon the Carboniferous continent. The lowest marine 
fauna of this division is seen in Parker county and careful study of 
the same may prove Jurassic affinities.” 
In a geologic section published, April, 1887 (Amer. journ. sc., vol. 
33, p. 299), the same author has placed his division of “ Dinosaur 
sand ” outside of the Lower Cretaceous, without assigning to it any 
special geological age, except that it is above the Carboniferous and 
below his Texas series of the Lower Cretaceous. 
Mr. II. T. Hill, in the Annual report of the geological survey of 
Arkansas for 1888, vol. 2, Mesozoic (Little Rock, 1888), p. 121 
et seq., calls his Dinosaur sands “ the Trinity Division of the Lower 
Cretaceous,” and gives a description of it in Texas, with a chapter on 
the “paleontology of the Trinity Division.” 
Mr. Hill has maintained his classification of the Trinity beds in the 
Lower Cretaceous in a paper entitled North American Cretaceous 
history (Amer. journ. sc., April, 1889, vol. 37, p. 290); and also 
in his Check-list of the Cretaceous invertebrate fossils of Texas 
(Austin, 1889). 
In a review of the Annual report of the geological survey of 
Arkansas for 1888, I have given reasons for dissenting from the view 
of Mr. Hill, showing that all the fossils described by him, instead of 
being Cretaceous, are Jurassic forms; and in conclusion, I say, “The 
Trinity division corresponds with the Upper Jurassic from the Pur- 
beck down to the Oxfordian inclusive” (see Jura, Neocomian, and 
chalk of Arkansas, in Amer. geologist, December, 1889, vol. 4, p. 
357-367). 
The Geological survey of Texas in its four annual reports from 
1889-1893 has accepted and used the classification of Mr. Hill, and 
regards the Trinity division, called since 1892 “the Bosque division,” 
as belonging to the Lower Cretaceous. 
