3 o2 STUDIES IN FOSSIL BOTANY 



zoic stem. The phloem, with its large sieve-tubes, is 

 well- shown in good specimens on both sides of the 

 wood, and the protoxylem can be recognised, forming a 

 number of small groups on the inner edge of the xylem, 

 which is thus endarch (Fig. 114). Its position in the 



Fig. 114. — Psaronius Renaulti. Part of transverse section of stem, showing a portion 

 of the solenostele. On the left is the edge of a leaf-gap. In the stele, note the 

 protoxylem-groups on the inner edge of the wood. The phloem, with large sieve- 

 tubes, is well preserved on the outer side. The dark elements in the pericycle are 

 secretory sacs. X r3. S. Coll. 2174. From a photograph by Mr. Tams. 



numerous steles of the more complex species may be 

 similar, but requires further investigation. 



P. Renaulti may provisionally be regarded as the 

 most primitive member of the genus. In a specimen 

 probably referable to this species Mr. Butterworth made 

 the interesting discovery that some of the roots show a 



