EARLY PENNSYLVANIA FLORA FROM WEST-CENTRAL ILLINOIS 27 



Discussion . — Alethopteris lonchitica is very common in the Spen- 

 cer Farm Flora. Several terminal portions have been found shoving the 

 long, lanceolate terminal pinnule. Some specimens are complete enough 

 to show the change from simple pinnatifid structure at the tip to two 

 orders of pinnatifid form farther down. 



A single specimen (ISM ^16129) of the near-terminal portion of 

 a pinna has unusually long, lanceolate pinnules (text fig. 9D). The 

 longest has a length of 3.2 cm and a length to width ratio of 5.3:1. 

 Similar size variation is found in other species of Alethopteris (for 

 example, A. serli). 



Alethopteris lonchitica is most common in the Westphalian A and 

 B, but is known from Namurian B through the Westphalian D (Gothan and 

 Remy, 1957, p. 118). Our specimens compare closely with the forms found 

 in the Namurian B of Vorhalle, Germany. 



Sphenopteris preslesensis Stockmans and Williere 

 Text fig. 10A, B; pi. 10, figs. 1-5 



Description . — Pinnules appear to be pedately divided, whereas 

 the veins have a pinnate division. The incisions between the lobes are 

 deep, and there is in many specimens a central incision that divides the 

 pinnule into two halves. The tips of the lobes are rounded to acute, 

 but often appear to be truncated owing to preservation. The size of the 

 pinnules vary somewhat depending on their position in the frond or in 

 the pinna. Pinnules are h to 6 mm long and 2.5 to k mm wide. They are 

 attached at angles from less than 50° to 70°. Pinnules have k to 10 

 lobes; 6 lobes are most common. 



Pinnae are 9 to 20 mm long and 5 to 10 mm wide. They are attached 

 at angles of 50° to 90°. Pinna axes are 0.3 to 0.6 mm wide, straight 

 to flexuous, and faintly alate. Axes of lower order are about 1 mm wide. 



No aphleboid pinnules were observed. 



Discussion . — Sphenopteris preslesensis is one of several Sphenop- 

 teris species with highly lacerated foliage that occur in the Namurian 

 and lowermost Westphalian. It is characterized by the fan-shaped ap- 

 pearance and nearly bilateral symmetry of the pinnules. Sphenopteris 

 preslesensis is known from the Namurian B of Belgium and Germany. 



Eusphenopteris morrowensis (D. White) van Amerom comb. nov. 

 Text fig. 11A, B, D; pi. 11, figs. 1-1+ 



Basionym: Diplothmema morrowensis 



19^+3 David White, Lower Pennsylvanian species of 

 Mariopteris , Eremopteris , Diplothmema, and 

 Aneimites from the Appalachian region: U.S. Geolog- 

 ical Survey Professional Paper 197-C, p. 99-100, 

 pi. 3k, fig. 1; pi. 35, fig. 1 



Text fig. 9 - Fossil plants from the Spencer Farm Flora. A-D, Alethopteris lonchitica. 

 Bar scales are 5 mm long. 



