433 
of Bennettites gibsonianus , Carr . 
altogether. These hairs are so very peculiar and differ so 
greatly from the simple unicellular twisted bristles which 
take their place in Cycas and Dioon , that we may devote a 
few words to them. They are leaf-like and resemble the 
ramenta of Ferns; radial longitudinal sections show that they 
possess considerable length, and are folded repeatedly be- 
tween and with one another in relation to the space which 
they have to occupy. Owing to these flexures and folds, we 
never see them in their full extension in surface-sections ; 
and for the same reason I have never been able to form a 
clear idea of the nature of their margin, and still less, of course, 
of their general figure. They are spindle-shaped in trans- 
verse section, and have a sharp edge to the margin on both 
sides. They are usually composed of a single layer of cells, 
but not unfrequently of two layers lying one on the other ; 
and in the middle they may contain as many as three layers, 
but at the margin there is never more than one layer. All 
their cell-walls appear to have been strongly thickened, and 
are broad, homogeneous, and of a dark brown colour ; in 
many cases indeed the secondary thickening-masses can be 
distinguished from the evident and lighter coloured middle 
lamella. The appearance of the transverse section of the 
hairs is admirably represented by Carruthers and also in 
Corda’s figures which belong to Zamites Bucklandi , and were 
incorrectly explained by this author, who took them for the 
macerated remains of the cataphyllary leaves between 
the leaf-bases. Tangential preparations show us the shape of 
the cells, which are elongate-tubular, with oblique ends thrust 
in between one another. 
Nathorst 1 2 has suggested that the fructifications of Ben- 
nettites gibsonianus may have been parasitic on the stem of 
Cycads, and has attempted a comparison of them with the 
genus Lophophytum. If any further argument against this 
view were still wanting, to which the author of it himself no 
1 Carruthers, loc. cit., pi. 60, figs. 7 and 11. 
2 Nathorst, ‘ Nagra anmarkningar om Williamsonia , Carr./ Ofversight af Kongl. 
Vetenskaps. Akad. Forhandlingar. 1880, No. 9. 
