3fi{« 
ON THE CLASSIFICATION OF THE DYAS, TRIAS 
AND JURA IN NORTH-WEST TEXAS. 
By Jules Makcoi', Cambridge, Mass. 
Tu the Second and'Third Anninil Reports of the Geologieal Sur- 
vey of Texas, Austin, 1891-1892, Mr. W. F. Cummins has given 
the following classification and nomenclature for the strata in 
north-west Texas. He begins with the Carboniferous or Coal 
Measures, divided into six great formations, which he calls: 
Bend, Millsap, Strawn, Canyon, Cisco and Albany divisions. I 
shall make no remarks on the Bend, Millsap and Strawn divi- 
sions. 
The Canyon division, so-called on account of its development 
at Canyon, in the western part of Palo Pinto county, contains a 
fauna entirely Carboniferous. It is a well defined formation, and 
easy to recognize in central and northern Texas. 
The Cisco division is well exposed at the town of Cisco, on 
the Texas and Pacific railway. The stratigraphy, lithology and 
paleontology differ so much from what exist in the^ Canyon di- 
vision, that it seems as a first great group of another stratigraphie 
system, or at least a passage formation between the true Carljon- 
iferons and the Dyas (Permian). In it are found a certain num- 
ber of Dyassic forms, such as: AUorisma, An'cuht. Aviculopecten^ 
Nacidd, etc. A careful palffiontologic investigation, as well as 
good and minute stratigraphie observations are much wanted. 
For the present I am inclined to regard it as the base of the 
Dyassic system, and related to the group which (exists on the south 
side of the mouth of the Platte river, at Plattsmouth City (Ne- 
braska). 
The Albany division, named for the reason that in the vicinity 
of Albany, in Stackelford count}', the strata are well developed,, 
correspond exactly to the Dyas of Nebraska City (Nebraska): liav- 
ing the same fauna, lithology and stratigraphie position. 
In the Second Amnml Report, Geo]. Snrv. Te.rus, at p. ;>9o,. 
there ''is a complete list of fossils of the Coal Measures," in 
which the fossils belonging to the Cisco and Albany divisions are- 
confounded with the fossils of the Canyon and Strawn divisions. 
That list needs to l)e revised, not only for the exact stratigraphie- 
