100 Hill — The Invertebrate Fossils of the 



northwestern Travis county, and the Edwards plateau to the 

 south, where its surface outcrops, owing- to rain sculj^ture, is 

 weathered into extensive fields of " Karrenfelder '' or miniature 

 mountains. 



The limitations of this group of strata have not heen finally 

 determined, but it should include as its upper members the 

 Austin marble (the Upper Caprotina limestone and the litho- 

 graphic flags of my local Austin section). No abrupt break is 

 evident between these and the underl3'ing beds which contain 

 the Comanche Peak fauna of Shumard (Die Kriedebildungen 

 bei Fredericksburg of Eoemer). The detail of these beds at 

 Austin have been given by Mr. J. A. Taff' (who made the section 

 under my supervision) in the Third Annual Report of the Texas 

 Geological Surve3^ 



Stratigraphically the Caprina limestone represents the (culmi- 

 nation of the subsidence that progressed during the Comanche 

 epoch. 



Paleontologically the Caprina limestone beds are of the great- 

 est interest, for in them we have the development of the aber- 

 rant Chamiche and Budistcs of this country. They contain all 

 the species of these families known to occur in the Cretaceous of 

 the United States, with the two exceptions of the Ca])rotina-like 

 CoraUiochama of California and the large Radiolites austincnsis- 

 like forms so common in the equivalents of the Colorado group 

 of the Upper Cretaceous in the Alabama, Texas, and Colorado 

 regions. As it is clearly and distinctly overlain by the whole of 

 the Washita division which corresponds to the Gault of Europe, 

 as will be later shown by the writer, and is above the well- 

 defined beds of the Trinity and Lower Fredericksburg division, 

 it affords an important landmark in tracing the progress of 

 marine life on this side of the ocean. 



II. — Characteristic Fossils. 



The fauna of the Caprina limestone has been little understood, 

 owing to the unfortunate fact that many of its fossils bave been 

 attributed to other horizons. Shumard* included the Lower 

 Caprotina limestone of the Trinity division in Hood county 

 with the Caprotina limestone of the Caprina beds, and through- 

 out his valuable literature one fails to find an}' distinction be- 

 tween them. A few 3^ears since my friend, Mv. George Stolley, 



* Loc. cit., p. 584. 



