2 Johnstone, Calamites {Ca/mnitina) varians, Sternb. 



biternodes. The stem is divided up into nine inter- 

 nodes and is crossed by two lines of branch scars. The 

 internodes are of very unequal length and the irregularity 

 appears to be periodic : the interest attached to the stem 

 lies partly in this. For reasons set forth below, A {Plate) 

 is regarded as the top region. The lengths of the inter- 

 nodes, (i) being at the highest level, are : — 



(i) lo mm. "j 



(2) 10 ,, > Incomplete Group. 



*(3) II ., j 



(4) 15 >. \ 



> Complete Group. 

 (6) 10 „ j ^ ^ 



*(7) 12 „ j 



(8) 25 ,, ) 



\ Incomplete Group. 



(9) 20 „ ) 



Total length 123 ,, 



It is evident : — 



id) That there are present one complete group of 

 internodes, the upper members of a second, and the lower 

 members of a third. 



(/;) That i, 2, 3 and 5, 6, 7 constitute two similar sets, 

 the lowest internode of each of which is a branch inter- 

 node, and the other two are the shortest in the series. 



(r) That, whereas the shortest sections stand above 

 the branch level, the longest in each case is beloiv it. 



id) That the short nodes are of uniform length. 



(e^ That there is an ordered sequence in the recurrence 

 of the shortened internodes. 



Surface Texture. I should judge the surface to be 

 a reproduction of the exterior of the woody cylinder, and 

 should identify as the only trace of cortical tissue present 

 * The branch scars lie in these sections. 



