326 R. T. HILL — GEOLOGY OF RED RIVER. 



done before, my recognition of this work * The study of these beds at 

 Preston and Fort Washita, and the discovery of their correct position in 

 the series, has given the writer an appreciation of Professor Marcou's 

 fossils that was not previously possible. 



Upon the question of whether the Kiamitia clays and Duck creek chalk 

 are or are not of the age of the Gault, I am not prepared to commit 

 myself, further than to say that the}^ present such striking paleontologic 

 resemblances to it that the}^ cannot be placed elsewhere, and that they 

 are certainly not Senonian, as first alleged by Dr G. G. Shumardf and 

 maintained by others. They succeed without break the Caprina lime- 

 stones, which are upper Neocomian beyond all reasonable doubt. 



The Kiamitia and Duck creek beds collectively can appropriately be 

 called Preston beds in honor of Professor Marcou's type locality, where 

 the beds are best exposed. Together they contain the following fauna : 



Kingena choctawensis, Shuniard, Pholadomya, sp. iiov. 



Epiaster whitei, Clark. Hamites (?) fremonti, Marcou. 



Holaster comanchesi, Marcou. Ammonites brazoensis, Shumard. 



Gryphxa forniculata, White. " belJcnapi, 'NLarcou.. 



" pitcheri, Morton. *' gibbonianus, Lea. 



Exogyra plexa, Cragin. " acute-carinatus, Shumard. 



Inoceramus, sp. nov. '' vespertinus (?), Morton (not A. 



Avicula leveretti, Cragin. texanus, Roemer, as has been alleged). 



This is one of the best defined and most specialized faunas of the 

 whole Comanche series. The Kingena choctawensis differs in shape from 

 K. ivacoensis, but may prove a variety of the latter species. The zone of 

 its occurrence is certainly far below that of the typical K. wacoensis. The 

 genus Inoceramus here in the Duck creek beds makes its only authen- 

 ticated appearance in the Comanche series. The undescribed species 

 resembles figures of I. neocomensis and /. labiatas of Europe, and is 

 entirely different in form from the Inocerami of the Upper Cretaceous. 



The Ammonitidse are especially.%ell differentiated and are worthy of 

 careful study. Only three of all the Duck creek species occur in other 

 beds so far as observed. 



Fort Worth Limestones. — These limestones succeed the highly marly 

 clays of the Duck creek chalk without perceptible break, and the sedi- 

 mentation between them is continuous. 



In the Denison section they have, as at Austin, the same alternations 

 of dimension layers and marls so characteristic of the beds there and 

 throughout their extent. The buff-white limestones (blue interiorly) 

 quickly disintegrate on weathering. These hard layers decrease in thick- 



* Bull. U. S. Geol. Survey, no. 45, p. 74 et seq. 



t Exploration of the Red River of Louisiana, etc., 1852. p. 158 



