R. T Hill — The alleged Jurassic of Texas. 463 



I am aware — Professor Marcou immediately proceeded to 

 announce, that* " The fauna of the upper part of the Jurassic 

 strata of Pyramid Mount at the Tucumcarri, thanks to the col- 

 lection made there in 1889 by Prof. A. Hyatt, is now well 

 known." 



Later, however, when he pressed Professor Hyatt, who has, 

 perhaps wisely, kept out of the controversy, for an opinion 

 concerning the age of the Ammonite, he received a very deci- 

 sive answer as follows :f " 1 think there can be no reasonable 

 doubt that it belongs to the Inflatus group of the genus Schloen- 

 bachia, hitherto found only in the Cretaceous." 



Not daunted by this decisive contradiction of the Jurassic 

 s^e of this species by Professor Hyatt, Professor Marcou next 

 proceeded to force the species into his Jurassic system, whether 

 or no, by making a new paleontologic law to suit the case as 

 follows: t( When considered in connection with the surround- 

 ing fauna of the Tucumcarri area, the Schloenbachia found 

 there indicates that in America the genus appeared near the 

 end of the Jurassic epoch, a fact constantly indicated for many 

 other fossil forms which appeared sooner in America than in 

 Europe.";): 



To demonstrate the last proposition he asserts that he§ 

 (Marcou), " received a very remarkable confirmation " of " his " 

 opinion concerning "the appearance of the Jurassic genus 

 Schloenbachia during the Jurassic epoch in America," and 

 says that Aguilera gives a description, with figure, of a 

 Schloenbachia "found among a whole Jurassic fauna" at 

 Catorce. By consulting the work referred to|| it is seen 

 that no such statement is made, and that the Mexican 

 Schloenbachia is not reported with the other Jurassic fossils 

 described by Aguilera, but is the only fossil found in the 

 limestone of the upper part of the upper division of their 

 section, and is referred by him to the upper part of the Lower 

 Cretaceous.^" 



The fact that he, himself, had originally given the Ammon- 

 ite a Cretaceous position — an insurmountable obstacle to its 

 alleged Jurassic occurrence in New Mexico — was further 

 remedied as follows : Mr. Dumble found a specimen of 

 Ammonites leonensis at Kent** in the same bed with the cog- 

 nate of G. pitcheri, which Marcou confessesff is his alleged 



* American Geologist, August, 1894, p. 102. 



f "The Jura of Texas," by Jules Marcou, — Proc. Bost. Soc. Nat. Hist., vol. xxvii, 

 p. 155. 



\ Same publication as above, p. 155. 



§ Proc Bost. Soc. Nat. Hist., p. 155. 



I Boletiu de la Commission de Mexico, Nam. 1, pp. 49 and 50 (Mexico, 1895). 



T]" Ibid., p. 49. ** Previously cited, p. 462. ff " The Jura of Texas," p. 153. 



Am. Jour. Sot. — Fourth Series, Vol. IV, No. 24.— Dec, 1897. 

 32 



