WARD.] THE SOUTHWESTERN AREA. 815 
and which has attached to its circumference a row of triangular 
teeth. . 
Taking everything into consideration, I think that the detached 
scales, and those that radiate from a central ring, called Z. ellipticus, 
are dissected stems of Zyuisetum Rogersit. They seem, while stand- 
ing erect, with their lower portions buried in mud and partly filled with 
the same, to have had the part above the mud crushed down by pres- 
sure in the direction of the axis of the stem. This split up the free 
end into strips. The forms such as are depicted in Fig. 4 of Pl. XLVII 
are detached diaphragms of the same Equisetum. ~ 
THE SOUTHWESTERN AREA. 
We will next consider the extensive beds chiefly in New Mexico and 
Arizona, but probably reaching into Texas on the east, and certainly 
found in the State of Sonora, in Mexico.’ They are doubtless also the 
equivalents of beds much farther south, near the City of Mexico and 
in Honduras, from which fossil plants have been reported.’ 
1 The following correspondence shows that the localities in Sonora ‘are by no means exhausted, and 
it is much to be hoped that the plant-bearing beds may yet be traced across the Rio Grande into 
Texas: 
NOEL, VIRGINIA, July 24, 1899. 
Prof. LESTER F, WARD. 
DEAR Sir: Some time ago Prof. I. C. White sent me a small box of fossil plants, obtained by 
Mr. Dumble, from Mexico. There were some six or eight species, mostly new. To judge from a 
slight study of them, I was struck with the perfection of their preservation and the adaptation of 
the slate to give good specimens. I sent a letter, through Professor White, saying that I thought the 
nearest plants to them were Newberry’s New Mexican copper mine fossils. As the material was so 
promising and seemed to yield so many good plants, I asked Mr. Dumble if he could get more speci- 
mens. I send you his reply. Please return it after reading. The slate splits almost like roofing 
slate, and seems full of plants. A good collection of it would, I think, help immensely to our knowl- 
edge of the Triassic flora of America, giving splendid material. 
Yours truly, Wma. M. FONTAINE. 
Houston, TExas, July 18, 1899. 
Prof. WM. M. FoNTAINE, 
Noel, Virginia. 
DeEaR Sir: Dr. I. C. White has inclosed me your letter of July 3. The plants are from the Triassic 
coal beds of Sonora, Mexico, the most of them being from La Barranca, where I am now working, 
and only a few miles from the locality at which the plants described by Dr. Newberry were col- 
lected. I have been unable to secure a copy of his paper, but a list of his determinations is given by 
Aguilera in his Geological Sketch of Mexico, and I have copied it in my Notes on the Geology of 
Sonora, New York meeting of the A. I. M. E., of which I will send you a copy as soon as my sep- 
arates arrive. The field isa very interesting one, as it contains large bodies of anthracite coal and 
of natural coke. Ihave found no less than 31 distinct beds of coal, the most of which are more 
than 4 feet thick. The igneous rock has been forced in along the bedding planes and produces 
quantities of excellent coke, one bed of which I have opened to a depth of 130 feet and find it has 
an average thickness of over 8feet. The slates are filled with well-preserved plant impressions and 
there are many large silicified tree trunks in the sands. 
I will probably spend the ‘next winter in the field, and if you would like to study the plants we 
can probably arrange to get you as large a collection as you can possibly wish. 
Yours very truly, E. T. DUMBLE. 
2See a letter from Professor Fontaine in the Eighth Ann. Rept. U. S. Geol. Survey, for 1886-87, 
Washington, 1889, p. 825, relative to a collection made in the vicinity of the City of Mexico and 
brought to Washington by Sefior Mariano Barcena in 1884. In 1890 Sefior Castillo brought another 
collection, which I examined, and Castillo and Aguilera, in their Bosquejo Geolégico de Mexico 
(Boletin del Instituto Geologico de México, Nos. 4, 5, and 6, Mexico, 1897), p. 208, give a list of the 
species which they were able to identify from these beds. See also Dr. Newberry’s article in the Am. 
Jour. Sci., November, 1888, 3d series, Vol. XXXVI, pp. 342-351, pl. viii. 
