Hick, on Rachiopteris cylindrica, Will. 



Explanation of Figures on Plate 1 . 



Fig. I. Transverse section of Rachiopteris , showing un- 

 divided stele. This photograph is taken from 

 slide No. 104 of the Cash Collection in the 

 Manchester Museum. 



Fig. 2. Transverse section, showing division of stele 

 into two equal parts (Cash Coll., No. 105). 



Fig. 3. Transverse section, showing unequal division of 

 stele (Cash Coll., No. 103). 



Fig. 4. Transverse section taken a little higher up than 

 section 3, showing beginning of separation of 

 the two unequal steles (Cash Coll., No. 102). 



Fig. 5. Transverse section, showing completion of divi- 

 sion of the stele (Cash Coll., No. 101). 



Fig. 6. Photograph of a larger portion of slide No. 

 102, than in Fig. 4 showing two stems, A and 

 B, with their offshoots ; a and r are probably 

 lateral roots ; and s is a lateral structure of 

 unknown nature. 



