EARLY PENNSYLVANIA FLORA FROM WEST-CENTRAL ILLINOIS 



preserved up to 5 cm long. They extend from the stem at angles of 30° 

 to ^5°. In three specimens, they overlap two nodes. The leaves and 

 stems are striated. 



In our specimens, only six to eight leaves are visible in each 

 verticil, "but this may be the result of preservation. In other aspects, 

 the specimens conform to published descriptions of A. longifolius. 



Asterophyllites cf. equisetiformis 



Three very small specimens of Asterophyllites have been found in 

 the Spencer Farm Flora. They are too poorly preserved to allow a pre- 

 cise identification, but are similar to A. equisetiformis in overall 

 proportion and form. At least 12 leaves were present on each verticil. 

 The leaves extend from the axis at almost 90° and then curve upward. 

 They are narrow and slightly overlap the node above. The leaves are 

 7 mm long and 0.5 mm wide, and the midvein is approximately 0.2 mm wide. 

 Although no complete whorl is preserved, it is clear that originally 

 there were at least 12 leaves per whorl. The internode length is 2.0 mm. 



Mesocalamites cf. cistiiformis (Stur) Hirmer 

 Text fig. UD, E; pi. 1, fig. 3 



The Spencer Farm Flora contains 1^ specimens of calamitean pith 

 casts and impressions. All determinable data on these specimens are 

 given in table 2. The most meaningful characteristics are (l) the con- 

 tinuity of the ribs, (2) number of ribs per centimeter, and (3) length- 

 to-width ratio of the nodes. 



On most specimens a majority of the ribs pass continuously across 

 the node whereas the others alternate. The narrow stems, however, which 

 bear the Calamostachys cones, do not show any alternating ribs. This 

 variation seems to exist only on very thin, fertile branches, and does 

 not indicate a specific or generic difference. 



Calamostachys andanensis Stockmans and Williere 

 Text fig. i+F-I; pi. 1, figs. 2, 7 



There are about ten specimens which can be attributed to Cal- 

 amostachys; apparently all of the specimens belong to one species. 



Description . — Whorls of bracts alternate with whorls of sporang- 

 iophores. The sporangiophores bear four sporangia which were probably 

 attached to a plate. The axes of the sporangiophores form right angles 

 with the main axis and are attached in the middle between two whorls of 

 bracts. The measurements are given in table 3. 



The specimens are well preserved in the siltstone and compaction 

 during early diagensis was slight. Nevertheless only a few characteristics 



Text fig. k - Fossil plants from the Spencer Farm Flora. A, Lepidodendron 

 wortheni leaf cushions. B, C, Annularia cf. vernensis , C- partial re- 

 construction. D, E, Mesocalamites cf. cistiiformis . F-I , Calamostachys 

 andanensis , F- complete cone, G- cones attached to Mesocalamites cf. cis- 

 tiiformis, H- reconstruction of part of the cone, I- reconstruction, view 

 into one verticil. Bar scales are 5mm long. 



