470 Systematic Paleontology 



minated abruptly by a pair of leaflets variously coalesced or the three 

 apical leaflets may be variously united^, their lamina may be almost 

 symmetrical or markedly inequilateral, their margins showing a tendency 

 toward undulation and occasionally a leaflet is divided into a basal and 

 an apical part by a sharp constriction on one side near the middle of the 

 blade. Ranging in size from the small forms upon which Fontaine 

 founded his species S. parvifolia and which are 1.6 cm. long and 0.4 cm. 

 wide to forms which approach 8. magnifolia in size and are 10 cm. 

 long and 1.5 cm. wide. The average dimensions of a large number of 

 specimens are, however, 6 cm. to 7 cm. long by 1 cm. to 1.3 cm. wide. 



Leaves thick with smooth surface. Eachis and midrib stout. Vena- 

 tion more prominent than in the other species but still very faint, with 

 the exception of the secondaries which while fine are more conspicuous 

 than in the other species. Secondaries forming a wide angle with the 

 midrib, nearly straight for 2/3 of the distance to the margin where they 

 bend sharply upward and join the secondary next above by a but 

 slightly curved arch. As the secondaries are numerous and almost uni- 

 formly spaced the venation has much the appearance of a Eucalyptus 

 except that the marginal hem is much broader than in that genus. 



This species is exceedingly abundant at various localities in the 

 Patapsco formation and is by far the most characteristic species of that 

 formation, althgugh it has not been detected at certain other undoubted 

 Patapsco horizons. It is the only species of the genus which has been 

 recorded outside of the Maryland- Virginia area, occurring in the Fuson 

 formation along Oak Creek, Wyoming, where it is the most abundant 

 species found just as it is at White House Bluff, Brooke, and Aquia 

 Creek, Virginia, and at Ft. Foote, Maryland. 



It is an exceedingly variable form in all its details, and as during 

 maceration the most variable apical portion is the last to be destroyed, 

 this variability is emphasized in fragmentary material such as that 

 usually found at Fort Foote. When well preserved it furnishes most 

 striking specimens as may be seen from the specimens reproduced photo- 

 graphically. In life its rigid pinnate leaves and strict appearance must 

 have made it a very striking member of the Patapsco flora. 



