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THE AMERICAN NATURALIST [Vol. XLVIII 



the converse is true in the later leaves, where the sinuses 

 separating the terminal lobe are the most shallow. I 

 have identified this form with Shull's simplex} 1 My 

 plants also agree fairly well with the illustration of onto- 

 genetic succession of leaf forms in Bursa . . . simplex, 

 shown by Shull. 12 



Type 2. — In the second of the two forms distinguished 

 because of the greater relative width of their first leaves, 

 the margin of the first five leaves remains entire, as in 

 the case of those of type 1 {simplex). The sixth leaf, 

 however, ordinarily shows a marked indentation, at least 

 3 mm. deep and slightly below the middle of the blade 

 (Fig. 4). This indentation may appear in one margin or 

 in both. The lower margin of the sinus ordinarily is at 

 right angles to the midrib, the upper margin making an 

 angle of 45 degrees with the midrib ( Fig.7, b ) . Even when 

 it has become difficult to distinguish between types on the 

 basis of relative width of the earlier roset leaves, it always 

 is possible to distinguish between type 2 ( rhomlwirJea) 

 and type 4 {Seichelliana and Treleaseana), by means of 

 the character of the sinus. In type 4, the lower margin 

 of the sinus makes an angle of 45 degrees with the midrib, 

 while the upper margin makes an angle of between .*!<> 

 and 45 degrees with the midrib. Hence the first sinus in 

 C. . . . Setchettiana and C. . . . Treleaseana is at least 

 90 degrees, while the first sinus in rhomhoidea measures 

 seldom more than 45 degrees and frequently less. 



narily shows two indentations on both sides of the leaf, 

 dividing the blade into a lower portion, two central lobes 

 and a terminal lobe. The depth of the incision amounts 

 to about three-fourths of the width of the blade from mid- 

 It is possible to delav the appearance of the first inden- 

 tations by transplanting from seedpan to flat either too 

 early or too late. In such cases, -the indentations appear 

 in the seventh leaf only, or even later, and are rather 



