92 



I regard it as younger than the Washita limestone and place it below 

 the Austin limestone. 



The Caprotina limestone is the lowest member of the cretaceous 

 strata of Texas. I have seen it on the False Washita, near the 

 Canadian, resting unconformably on the Trias, and passing by almost 

 insensible gradations to the Gryplio^a Pitcheri limestone. The list of 

 fossils given by Dr. Shumard indicates a Neocomien fauna. As Dr. 

 Shumard cites the foot of Mount Bonnell as one of the typical 

 localities for the Caprotina limestone, it is to be regretted, once more, 

 that he did not give an exact real section of that mountain. 



Without giving a single locality where the Caprotina limestone may 

 be seen clearly and unquestionably overlying the Arenaceous group, 

 Dr. Shumard makes a great division which he calls Lower Cretaceous^ 

 and which, according to his brother, contains, in its upper part, Ostrea 

 congesta, Ptychodus mammilaris, Lamna compressa, Lamna Texana, 

 and Galeocerdo cristodontus. I found the Ostrea congesta at Galisted 

 (New Mexico), in company with Inoceceramus prohleryiaticus, Ptyclio- 

 dus Whipplei, and a large Ammonite, and I have referred those strata 

 to the Chalk group of Europe. From the fossil fishes determined by 

 Dr. Leidy, I consider the Arenaceous group of Dr. Shumard younger 

 than the Washita and Comanche Peak group, and of the same age 

 with the fish-bed at the base of the Austin limestone and the Blue marl 

 of Grayson County. The Lamna Texana is, according to Dr. Shu- 

 mard himself, common to the Arenaceous group and the fish-bed of 

 the Austin limestone ; and the Ptychodus mammilaris is a very charac- 

 teristic fossil of the chalk of France, England, Belgium, Italy, and 

 Germany ; so I see no reason, paleontologic or stratigraphic, for 

 placing that division in the Lower Cretaceous rocks. 



Marly clay or Red River group. This group is an interesting 

 addition to our knowledge of Texan cretaceous rocks. From its 

 position below the Arenaceous group, and from the fauna contained in 

 it, such as Ammonites, Ancyloceras, Scaphites, Baculites, &c., all new 

 species related to the Marly Chalk species of Europe or America, I 

 regard it as a part of the Upper Cretaceous, below the Austin 

 limestone and the blue marl vnth Inoc. proUematicus, but above the 

 Caprina limestone. I think it fills up the gap between the deposit of 

 the cretaceous strata of the table-lands and those of the plains of 

 Texas. 



Now, if I arrange, in a tabular form, the groups of Dr. Shumard, 

 as I am led to consider them, we shall have the following table : — 



