PENNSYLVANIA TREE FERN COMPRESSIONS 



11 



Caulopteris/Psaronius sp. 

 Text fig. 7, E; pi. 2, figs. 2-4; pi. 3, fig. 1 



Three specimens of Caulopteris (Field Museum PP 11797, PP 11798, 

 PP 17785) show traces of the vascular bundle in the stem. The stems are 

 preserved as ironstone casts found in the Francis Creek Shale near 

 Wilmington. 



In the specimens three or four circles of vascular bundles are 

 present. They are always somewhat removed from their original position, 

 and the stems are in some places incomplete at the margin. Sections 

 are shown in text figure 8. 



In specimens with this type of scar, the scars are far apart. 

 From the outside, the leaf scars are quite different in appearance from 

 those described in Caulopteris sp. A to D. In Caulopteris /Psaronius sp. 

 the leaf scars are elongate and open on one end. This narrow, open end 

 is probably the lower end of the scar. The orientation is best derived 

 from examination of specimen PP 11797 (pi. 3, fig. 1), in which the 

 upper margin of the leaf scar comes out of the stem. 



Specimens To Be Excluded 

 from Caulopteris 



Several specimens identi- 

 fied as Caulopteris should be 

 transferred to other genera: 

 "Caulopteris" radicans (Lesquereux, 

 1866) Janssen, 1940, is a decorti- 

 cated lycopod stem. "Caulopteris" 

 acantophora Lesquereux, 1870, is a 

 mass of hairy axes or roots. "Cau- 

 lopteris" langfordi Janssen, 1940, 

 is a Lepidophloios as recognized by 

 Langford (1958). The specimens 

 figured by Langford (1963, p. 175- 

 179) as Caulopteris are actually 

 root mantles of tree ferns (fig. 

 757a and b) , a problematicum (figs. 

 758-760) , and decorticated lycopod 

 stems (figs. 761-765). 



DISCUSSION 



Text fig. 8 - Cross sections through 

 specimens of Caulopteris /Psaronius 

 sp. from the Francis Creek Shale 

 of northern Illinois. A-C, specimen 

 PP 17785, sections about 25 mm apart; 

 D-E, specimen PP 11797, sections about 

 85 mm apart; F-G, specimen PP 11798, 

 sections about 230 mm apart. 



The characteristics used 

 in classifying stems of Paleozoic 

 tree ferns are: 1) shape of vas- 

 cular bundle and 2) the presence 

 of two rows or more than two rows 

 of scars in the mature stem. On 

 the basis of these characteristics, 



