PLATE XXVII. 



1. Section through pinnule joint. 



2. Section through arm joint. 



3. Edge of same, somewhat more magnified. 



4. Section across top of first radial. 



5. Longitudinal section of joint near the middle of the stem (Plate XVII. Fig. 12, a). 

 I). Transverse section of joint near base of stem (Plate XVIII. Fig. 9, a). 



These figures are from photographs by Dr. R. R. Andrews, taken from sections made by Dr. 

 Heusoldt, of the Columbia School of Mines. 



