Manchester Memoirs, Vol. xliii. ( 1 899), No. %, 5 



cannot be distinctly identified, though a couple of layers 

 of cells, probably constituting the cambium, can be dis- 

 tinguished around the secondary xylem. In Fig. 2, it 

 can be seen at some places in contact with the secondary 

 wood, and in other regions widely separated from it. The 

 inner and outer layers of the cortex are both noticeable 

 in such old roots, but on the outside of the outer cortex 

 there are no longer any of the numerous hairs which form 

 so characteristic a covering to the young roots. 



Since my communication was read before this Society, 

 I have carefully re-examined all my sections and re-read 

 the published memoirs on Heterangium tilioides and 

 Heterangiiini griveii, and, notwithstanding that my con- 

 clusions that the new Psaronins which I have discovered is 

 the root of H. tilioides are doubted, I am still of opinion 

 that these Psaronius roots belong to a form which has 

 close affinities with //. tilioides, and thus represents a 

 link between the Psaronius of Corda and Heterangium 

 with its extensive secondary thickening. Until, however, 

 the stem belonging to my new root is discovered, I wish 

 it to be known as Psaronius cromptonensis, in recognition 

 of the richness of the locality of Crompton in coal- 

 measure plants. 



I have to acknowledge my indebtedness to the 

 authorities of Owens College for placing several sections 

 of Heterangium at my service for examination during this 

 investigation, and have also to thank Prof F. E. Weiss 

 for his kind help in these labours. 



