COMPARISON OF VARIOUS WASHITA LOCALITIES. 383 



Rose beds into the Wasliita is additional evidence of tlie unit}^ of the 

 deposits grouped together as the Lower Cretaceous series. The recur- 

 rence of so characteristic a fossil as Grypluwi dllatata, of the Jurassic, in 

 its varietal form of G. iacumcarU, Marcou, in the base of the Washita, at 

 Kent, has also been noticed.'^ 



Another case is that of Exogyra ariet'uia, Roeni., which, even as far 

 west as the Pecos, overlies the Washita limestone, while in the Sierra 

 Blanca section it is, according to TafF, within 100 feet of the base. In 

 the Malone mountains I found the Xodosarla bed, which is part of the 

 Exogi/ra arktina beds, underlying a Caprliia bed, and Tatf found the same 

 relation existing at the south end of the Quitman mountains. Kingena 

 {Terehratuhi) iracocnsis, Roem., is a form whicli, in the Austin section, be- 

 longs immediately below the ArietuKi. I found a Terebratala, in nowise 

 distinguishable from it, below the Caprliia bed of the Devils River sec- 

 tion as well as above that bed, and it ranges from bottom to top of the 

 Kent section. It was collected in quantities by Mr Streeruwitz from 

 Devils ridge, just west of the Eagle mountains. While it is easy to dis- 

 tinguish two or three very different forms, such as an elongate form 

 and anotlier which is nearly as broad as long, these are not confined to 

 separate horizons, but occur in the same bed, and when a sufHcient 

 number have been collected all intermediate stages can ])e readily found 

 in them. 



Upper Cretaceous. 

 geologic succession and correlations. 



My first section of the Rio Grande Cretaceous, in " Notes on tlie Geology 

 of the middle Rio Grande," t gives the general succession of beds l)etween 

 Del Rio and the Cretaceous parting near the Maverick-Webb county-line. 

 The divisions there given were based principally on lithologic grounds, 

 although paleontologic differences were also noted. 



Beginning at the base, the Val Verde Hags, which were found overlying 

 the Vola limestone, were considered the equivalent of the Eagle Ford or 

 Benton shales (no trace of Dakota fossils having been observed). The 

 overlying Pinto limestone was evidently the continuation or the equiva- 

 lent of the Austin limestone, both lithologically and paleontologically. 

 The Upson clays, corresponding both in material and fauna with the 

 Ponderosa marls, followed, and were in turn succeeded by the San Miguel 

 beds, which were the supposed equivalents of the (dauconitic or Navarro 

 beds of tlie East Texas section. A subse({ucnt stud}' of a i)ortion of the 

 fossils of the San Miguel Ijeds by Dr C. A. White confirmed this, and lie 



•See Am. Geologist, November, 1893, pp. 309-314. 

 t Bull. Geol. Soc, Am., vol. 3. pp. 219-230. 



lA'— Bri.i.. «KOt.. Soc. Am.. Vol. 0. 1894. 



