Mesozoic Series of New Mexico- — Mareou. 151) 
thougli more than thirty years have elapsed since its publica- 
tion. The Mesozoic fossils arc rc])rescnted on five plates, well 
executed, and they are described under the names of: Ptycho- 
dus whipplei, Ani/nfmites s/iiunardi, Am. belknapii, Ani. 
peruvianus, Am. (fibhonianus^ Am. 7iovi-mexicani, Jlamitea 
fremonti, Inoceramus lerouxi., Isocardia ivus/iita, Gri/p/una 
sirmata var. ainericana, Grupfuea pitcheri, HolaKter com- 
anchesi, Grypheea dilatata var. tueu/nrarii, and Ostrcn mar- 
shii. (5) "Letter on some points of the geology of Texas, New 
Mexico, Kansas and Nebraska," Zurich LS58. And finally (6) 
"line reconnoissance geologique au Nebraska." (Bull. Geol- 
Soc. France, vol. xxi, pp. 121-14G, Paris, 18 Janvier 1864). 
Now let us give by order of dates the classifications of the 
geologists who have succeeded me, covering either partly the 
ground traveled over by me, or who without going at all into 
the field, have, however, expressed their views on the classifica- 
tion of strata and on Mesozoic fossils found in the same area 
1857, Hall. — Mr. James Hall, after having in his hands 
without my consent or even knowledge, my specimens,* and 
my field-notes book, besides making use of my general 
geological map of the United States, with the geological sec- 
tion from the Mississippi river to Los Angeles, and the plates 
of Mesozoic Ostraceie, came to the following conclusions, 
which he recorded first in IShQ ( Par i^c railroad explorations, 
4to edition, vol. iii, chapter ix), and second in 1857 {Mexican 
boundary survey, vol. i, pp. 135-136.) Here is his table of 
classification : 
n. — TaMe showincr the order of succession and classification of the 
Mesozoic series of Texas, the Indian torritorv and New Mexico, by 
James Hall. 1S57. 
TeKTIARV FiiKMATION. 
CRETACEor.sj and 
FORMATION I Middle 
of ICrotact'ous. 
Nebraska. 
\'. ArenaceoHH clay=Fox Hill group.' 
IV. Plastic clay=Fort Pierre group. 
[IL Calcareous mjirl= Niobrara division. 
IL Clay=Fort Benton group^ 
CreUceous. I^' ^^"^ston© ^^^ clay=Dakota group. 
Carboniferous formation. 
* They were place«l in his hands by order of the Chief of Engineers, 
thropgh Mr. AV. V. Hlako.— [Ed.] 
'In 18t)l, Meek and Ilayden applieil geographical names to the 
various division.s^retaining, however the original numbers. {Procffd. 
elnhi 
Acad. Xal. Sci., Philadelphia.) 
