462 H. T. Hill — The alleged Jurassic of Texas. 



accept them. This fauna is undoubtedly one of the oldest of 

 the Comanche Series. In my Arkansas report I said that it 

 resembled the Wealden and Purbeckian, a position which I 

 still maintain, and Professor Marcou has proved nothing 

 further concerning it. He has issued similar manifestoes upon 

 the appearance of other lists of species from the Southwest, 

 notably the one identified by Stanton and published by 

 Dumble from the Washita Division at Kent.* Here he takes 

 a dozen or more of the best known and commonest fossils, not 

 of Wealden affinities, but from the uppermost division of the 

 Lower Cretaceous, and refers each of them serially to Jurassic 

 forms. His ipse dixit is all the basis there is for such correla- 

 tions. 



The following extracts from Professor Marcou's discussions 

 of a species of Ammonites, a family of much more value for 

 stratigraphic correlation than Ostreidae, show that he, rather 

 than others, used the peculiar methods in paleontological dis- 

 cussions which he has attributed to them. He found no 

 Ammonites in the "Jurassic" Tucumcarri region, and noted 

 their supposed absence. In his " Geology of North America" 

 (p. 33, Plate I, fig. 1), he gave an excellent figure of a "Cre- 

 taceous" species which he named Ammonites shumardii, after 

 Dr. George G. Shumard, here called by him " the learned 

 geologist of Arkansas," who collected all the species from Fort 

 Washita and Texas, near Red River. These localities, which 

 Marcou has never seen, are several hundred miles distant from 

 Tucumcarri, and judging from his writings he is ignorant of 

 their stratigraphy, although they have been visited several 

 times by the writer and made a special study by him.f 



Furthermore, as I have seen, this species of Ammonite 

 occurs by the hundreds in the Red River localities from which 

 Marcou's type specimen was sent, in a horizon stratigraphically 

 below beds containing the majority of the species now known 

 to constitute the fauna of his alleged "Jurassic" of the 

 Tucumcarri region, and above the horizon of his Comet Creek 

 "Neocomian." 



In 1888 Professor Alpheus Hyatt found this confessedly 

 Cretaceous species of Professor Marcou's in the supposed 

 "Jurassic" beds of the Tucumcarri region of New Mexico. 

 Professor Marcou, since the latter event, endeavored to recon- 

 cile these facts in a most remarkable manner. Without await- 

 ing publication by Professor Hyatt, and upon what authority 

 we do not know — for Professor Hyatt has never published 

 other than a brief administrative report;}; on his work so far as 



* American Geologist, November, 1893. 



•f See papers previously cited. 



X Eleventh Annual Report U. S. Geological Survey, Part 1, pp. 97-100. 



