MARCOU : THE JURA OF TEXAS. 
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Nerinea. Mr. Ilyatt has collected several specimens of Ammonites 
which he refers to Ammonites Shumardi , identical with the A. 
leonensis of Mr. Dumble from the Kent section. He thinks, and I 
agree with him, that the A. leonensis Conrad is another and distinct 
species. He found it with the Gryphaea Tucumcarii , and there is 
therefore no doubt possible in regard to the contemporaneity of the 
Ammonites Shumardi and the Gryphaea Tucumcarii. Mr. Hyatt, 
who, at my request, kindly studied the Ammonites Shumardi says, 
“ I think there can be no reasonable doubt that it belongs to the 
Inflatus group of the genus Schloenbachia hitherto found only in the 
Cretaceous.” 
When considered in connection with the surrounding fauna of the 
Tucumcari 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. 
In August, 1895, I received a very remarkable confirmation of my 
opinion in regard to the appearance of the genus Schloenbachia 
during the Jurassic epoch in America. Don Jose G. Aguilera of the 
Geological Survey of Mexico, in the first number of the Boletin de 
la comision geologica de Mexico (Mexico, 1895, 4°), gives a descrip¬ 
tion with figure of a Schloenbachia, also of the group of Infiata of 
Sowerbv, found amonff a whole Jurassic fauna at the Mineral de 
Catorce in the State of San Luis Potosi (see Primeros estudios de 
la fauna f6sil de la Serrania Mineral de Catorce en San Luis Potosi, 
p. 18, pi. 9, fig. 1). 
A very small Ammonites also was found by Mr. Hyatt at the 
Tucumcari area; it is too imperfect for description, but resembles 
somewhat an Upper Liassic species of the Jura. In addition, he has 
collected a fragment of a very large Nautilus, which is not the 
Nautilus giyanteus of the Upper Jurassic of the Jura but resembles 
some of the very large cephalopods of Portland in England. 
Finally, Mr. Hyatt has found one isolated specimen of Pecten 
texanus Rom., near the Laguna Colorada, and one specimen of a 
fragment of a small Pecten resembling the Pecten quadricostatus 
Rom. These two fossils, rare at that locality, are the only Cretace¬ 
ous forms in Mr. Hyatt’s collection, which contains about thirty 
species. 
The conclusion reached in 1853, when I was at Pyramid Mount, 
Tucumcari, is confirmed by all I have seen since. The horizon of 
