— 16— 



two sets of hyemale, though the close agreement in most par- 

 ticulars will only emphasize the fact that this species is not 

 nearly as variable as has before been imagined. Extremes are 

 very few in number. Mr. Cocks' specimens were received still 

 attached to the rootstocks and each clump appeared to consist of 

 a few stems of large calibre, surrounded by others much smaller. 

 The larger stems appear to be the ones that bear fruit and this 

 possibly accounts for the large size of the specimens seen in col- 

 lections. Further observations upon this point are greatly de- 

 sired. It would be interesting to know whether there is any de- 

 cided difference between the two forms in what are usually 

 called specific characters. It is certain that the number of grooves 

 in the stem is not always greatest in the largest stems. All 

 measurements were made while the stems were fresh. 



MEASUREMENTS. 



Height. — Owing to the manner of growth, height is not of 

 special significance in Bquisetum. Data of this kind, however, 

 are interesting for comparison and the height of the specimens 

 measured are here presented : 



Height in Inches. 





25 





26 



27 



28 



29 



30 



83 Patterson sp... 





















3 



4 



S 









5 





2 



3 



2 







6 



3i 32 33 



34 35 



36 



37 



38 



39 



40 



41 



42 



Av. 



6 10 11 



8 11 



10 



4 



4 



5 



1 







1 



34 in- 



3 16 11 



9 10 



4 



5 



4 



8 



8 



2 



2 



34 in. 



The two forms thus appear of equal average height, though 

 owing to the small stems of robustum mentioned, the latter shows 

 the widest range. 



Diameter of Stems. — The diameter of the stem varies little 

 and may therefore be considered of great diagnostic value. The 

 table below will show this. 



Diameter in 32nds of Inch. 4 5 6 7 ' 8 q 10 11 Av. 



Sijolietsp 4 12 17 10 8 o o o 6X 



81 Patterson sp o o 26 35 18 2 o o 7 



122 Robustum 8 25 46 14 19 5 3 2 6X 



Again the average is practically the same, but distributed dif- 

 ferently. Without doubt if only mature fruiting stems of ro- 

 bustum were measured the difference in size would be greatly in 



