1887.] NATURAL SCIENCES OF PHILADELPHIA. 43 



less saline condition. It is also significant that, with the excep- 

 tion of some marine mollusca which Mr. Meek doubtfully referred 

 to the Dakota group in New" Mexico/ no other invertebrates than 

 those which the Kansas and Dakota localities have furnished, 

 have been reported as coming from that group. The facts which 

 have been mentioned, others which will be referred to, and our 

 present knowledge of the general geology of that western region, 

 all seem to indicate that while the greater part of the Dakota 

 group, as it is now known, is a non-marine deposit, we ought to 

 expect to find it to merge into a marine deposit to the southward. 



Now in making comparisons of the Texas Cretaceous rocks 

 with those which have been observed in other parts of the conti- 

 nent, we find that the whole Comanche series represents older 

 strata than are included in any of the other published sections 

 of North American Cretaceous except perhaps that of California.^ 

 The strata of the Comanche series are known to extend north- 

 ward from Texas into the Indian Territory, and some of its 

 characteristic fossils have been found in southeastern Kansas. 

 Fossils belonging to this series have also been found at various 

 points in western Texas and the adjacent southeastern part of 

 New Mexico. They have also been found at various jDoints in 

 Mexico, one locality being upon the western side of the Sierra 

 Madre, in the Mexican State of Sonora.^ 



Judging from all the information which I have been able to 

 obtain, I infer that none of the strata of the Comanche series 

 extend beyond the eastern boundaries of Texas, nor further 

 northw^ard than southern Kansas. It seems probable also, that 

 while this series is well developed, both faunally and strati- 

 graphically, in Texas, it has, or originally had, its greatest 

 development within the region which is now the Republic of 

 Mexico. 



Again, judging from present information, there seems to be a 

 comjjlete faunal bi'eak at the top of the Comanche series. That 

 is, I am not yet aware that a single fossil species of that series 

 passes up into any of the upper members of the Texas Creta- 

 ceous Section. The Comanche series is therefore not only greatly 

 restricted in its geographical extension to the eastward and 



1 Newberry's Geol. Report before cited, p. 121. 



'' White ; Bull U. S. Geol. Surv., No, Vol- 15, p. Ill, 1885. 



3 Gabb ; Paleontology of California, Vol. II, p. 257. 



