136 The Lower Ceetaceous Floeas of the World 



Cycadeospermum rotundatum Fontaine 



Dioonites DunTcerianus (Goepp.) Miquel 



Dioonites BucManus (Ettings.) Born. 



Dioonites BucManus rarinervis Fontaine 



Dioonites BucManus angustifoUus Fontaine 



Eguisetum texense Fontaine 



Frenelopsis varians Fontaine 



Frenelopsis Hoheneggeri (Ettings.) Schenk 



Pagiophyllum duMum Fontaine 



PaleoMllia arkansana Knowlton ^ 



Pinus ? sp., Fontaine 



Podozamites acutifoUus Fontaine ? 



Podozamites ? sp., Fontaine 



Sequoia pagiophylloides Fontaine 



Sphenopteris valdensis Heer ? 



Sphenolepis Sternbergiana (Dunker) Schenk 



? Thuyoxylon americanum linger 



WilUamsonia texana Fontaine 



Zamites tenuinervis Fontaine 



It comprises rather widespread Lower Cretaceous types of a resistant 

 character which withstood maceration in littoral marine deposits, and it 

 is therefore not sufficiently representative for close correlation. Only 

 1 fern is represented. The cycads number 8 species, and the conifers 

 11. Six Potomac species are more or less satisfactorily identified, and 

 3 additional are somewhat doubtful. 



The Trinity has been regarded by Hill as of l^eocomian age, although 

 representing a considerable time interval during its transgression. Dou- 

 ville,^ Kilian,^ Suess,* and others have advanced reasons for considering 

 the base of the Texas Cretaceous as not older than the Aptian, and the 

 flora cannot be said to offer any evidence contrary to this view. A 

 further fact which suggests that the Texas Lower Cretaceous as a whole 

 is younger than it has usually been considered is furnished by certain 

 Albian faunal elements said to be present in the Fredericksburg, and 



^ Knowlton, Bull. Torrey Bot. Club, vol. xxii, 1895, pp. 387-390, tf. 1-3. 



^Douville, Sur Quelques Rudistes Americains, Bull. soc. gSol. Fr. (ser. iii), 

 tome xxviii, 1900, p. 218. 



^Kilian, Sur Quelques gisements de I'etage aptien, IMd. (ser. iv), tome ii, 

 1902, p. 358. In Precli, Lethsea geognostica, 2 Teil, 3 Band, 1 Abt., Palaeo- 

 cretacicum, 1907. 



* Suess, Amer. Journ. Sci. (iv), vol. xxxi, 1911, p. 105. 



