152 TRANSACTIONS LIYEEPOOL BIOLOGICAL SOCIETY. 



6° 8. Martensii, Spr. Round this species must be 

 grouped the majority of the species of the genus, 

 diverse as they are in habit, all characterised by dorsi- 

 ventralry both of external morphological features and 

 internal anatomy. 

 7° S. uncinata, Spr. is a particular^ 7 interesting species 

 as giving the first indication of the tendency to form 

 at least three principal steles, placed dorsally, medianly 

 and ventrally, a feature seen on the highest division 

 of the group, and arising, as I have shewn elsewhere 

 [I.e.) in quite another way from the bistely of such 

 forms as S. Galeottei. 

 8° S. inaequalifolia, Spr. I look upon the series of 

 which this species is the anatomical type as represent- 

 ing the highest development of stem in the genus. 

 Here there are two principal accessory steles one 

 dorsal to the median stele (which latter alone bears the 

 ordinary leaf traces), the other ventral. The dorsal 

 stele arises from the fusion and isolation of dorsal 

 cords which in younger conditions result from the 

 fusion of the adjacent protoxylem strands of branch 

 and axis, v T hilsi the ventral stele carries the leaf 

 traces of the axillary leaves. 

 Let us now see whether the accepted classification of 

 the species by systematists is in accord with these anat- 

 omical peculiarities. In order to make the comparison 

 the more vivid I give in the left hand column the names 

 of the species I have examined microscopically arranged 

 in groups according to their anatomical structure and in 

 the right hand column the same species arranged accord- 

 ing to Baker's list. 



1° S. laevigata, Bak., var. 



Lyallii, Spr. I. Selagixella. (1) S. sinuosa, P.B. 



2° S. spixosa, P.B. (2) S, riqjcsti-is, Spr 



