EXOGYRA PONDEROSA ZONE. 



33 



although at present their ranges can scarcely be said to be known with sufficient defmiteness to 

 permit confident correlation. > 



Teeth and fragmental bones of reptiles, including dinosaurs, mosasaurs, crocodiles, and 

 turtles, have been found at numerous localities in the zone, but are for the most part too frag- 

 mentary to permit specific determination. Two species of crocodiles, Thecachampsa rugosa 

 Emmons, and Polydectes biturgidus Cope, from Roods Bend, Chattahoochee River, iden- 

 tified by C. W. Gilmore, are said by Mr. Gilmore to be identical with species obtained from 

 Phoebus Landing, Cape Fear River, N. C, an upper Black Creek horizon. The evidence fur- 

 nished by these forms tends, therefore; to corroborate the evidence afforded by the fossil inver- 

 tebrates. 



PLANTS. 



Fossil plants have been found at two localities in the Cusseta sand member of the Ripley 

 formation in Georgia. Stratigraphically, this member falls within that part of the zone pf 

 Exogyra ponderosa included between the Mortoniceras subzone and the base of the zone of 

 Exogyra costata. One of these localities is in Marion County, 6 miles northeast of Buena Vista. 

 E. W. Berry, to whom the plants were submitted, recognized six species from this locality, as 

 follows : 



Andromeda novaecsesarese Hollick. 

 Araucaria bladenensis Berry. 

 Eucalyptus angusta Velenovsky. 

 Doryanthites cretaceum Berry. 



Ficus georgiana Berry. 



Manihotites georgiana Berry (same as at McBride Ford). 

 Monocotyledon, gen. et sp. nov. (common to the Black 

 Creek and Tuscaloosa formations). 



Concerning these he says : x 



Three of the foregoing species occur in the underlying Eutaw formation, and all but the Ficus, which is new, are 

 found in the Black Creek formation of North and South Carolina. The Andromeda is a characteristic species of the 

 Black Creek formation and one of the type fossils of the Magothy formation of the northern Coastal Plain, although it 

 makes its earliest appearance in the Raritan formation, as does also the Eucalyptus. None of the six genera except 

 Ficus are represented in the flora of the Montana group, and the latter is represented by very different species. It seems 

 clear, then, that the Cusseta sand is pre-Montana in age and that it falls within the same general paleobotanic limits 

 that include the Magothy-Matawan, typical Black Creek, Middendorf, and upper Tuscaloosa floras of the East and the 

 flora of a part of the Dakota sandstone of the West. 



The other locality is in Houston County, lh miles northeast of Byron. Concerning these 

 Berry says : 



These plants number but three species — Dryopterites stephensoni Berry, Cunninghamites elegans (Corda) End- 

 licher, and Araucaria jeffreyi Berry, the first-named form being new to science. 



As Dryopterites occurs in the Lower Cretaceous, Dryopteris-like forms are found in post-Cretaceous floras down to 

 the present time, and Dryopteris (Aspidium) is to-day a widespread and dominant genus of ferns, the Georgia species, 

 which is unlike any of the described forms, is of no value in correlation. Of the other two forms, Cunninghamites ele- 

 gans has a rather wide geographic range, occurring both in this country and abroad, and a considerable geologic 

 range. In Europe it ranges from the Cenomanian to the Senonian, inclusive, and in this country it has a parallel 

 range, from the Magothy flora of the East to the Montana flora of the West. It has been recorded from Lower Cretaceous 

 horizons in Europe, but these determinations are believed to be erroneous. The nearest geographic occurrence to that 

 in Georgia is that of the upper part of the Black Creek formation of North Carolina; hence the conclusion that the 

 exposures near Byron are not older than those of the Black Creek and not younger than those of the Montana group 

 appears to be firmly established. 



The remaining species, Araucaria jeffreyi, is not a widespread form, and its intimate association with Araucaria 

 bladenensis in the Eutaw formation at Chimney Bluff, Ga., and in the Black Creek formation of North Carolina indicates 

 that it may represent cone scales of the latter species. Taken alone, Araucaria jeffreyi points to the same conclusion 

 regarding the age of the deposits near Byron as does the distribution of Araucaria bladenensis, but the latter furnishes 

 more definite data. 



Araucaria bladenensis is one of the most abundant and typical forms of the Black Creek formation in North and 

 South Carolina, ranging from its base to its summit. It has also been found in the Cusseta sand member of the Riplev 

 formation near Buena Vista, in the Eutaw formation just below the Tombigbee sand member at Chimney Bluff, and 

 in the base of the Eutaw formation in western Alabama. A closely allied or identical form occurs in the Magothy of 

 Maryland and New Jersey, and a similarly allied form has been described from the Turonian of Bohemia. 



1 Berry, E. W., The Upper Cretaceous and Eocene floras o J South Carolina and Georgia: Prof. Paper U. S. Geol. Survey No. S4 (in pressL 

 105°— No. 81—14 3 



