ORGANIZATION OF THE FOSSIL PLANTS OF THE COAL-MEASURES, 955 
Fig. 30. Part of a tangential section of a strobilus, showing a sporangiophore-pedicel 
(sp) in transverse section, surrounded by its 4 sporangia. The vascular 
bundle of the sporangiophore is seen. Parts of the adjacent whorls of 
coherent bracts, br, br, are shown. Three vascular bundles are shown in the 
lower, and two in the upper whorl. ©O.N. 1023. x 50. 
Fig. 31. Details of sporangium-wall, 
A. In surface view ; “ buttresses” seen (as at bw) projecting from cell-walls 
into interior of cells ; 
B. Jn transverse section of sporangium (tangential of strobilus). Here the 
‘buttresses ” (bu) are seen from the side, with the thin cell-wall between 
them. Such a section cuts across the cells shown in A. 
C. In longitudinal section of sporangium (transverse or radial of strobilus). 
Here the narrow edges of the “buttresses” (bw) are shown. Such a section 
cuts the cells shown in A lengthwise. The difference in the thickness of the 
wall in B and Cis accidental. C.N. 1003. x 200. 
Fig. 32. Part of a tangential section, passing through the peltate expansions of 
the sporangiophores (sp), 4 of which are shown, and also part of the whorl of 
bracts (b7) between them. In sp. 1 the right-hand dichotomy of the vascular 
bundle (vb) is well shown. In sp. 2 the section shows one bundle in transverse 
section, and a branch-bundle cut longitudinally. In sp. 3 parts of the vascular 
bundles are shown. At two points the section passes through the concavities 
of the under surface of the scale, and shows part of the wall of 2 sporangia, 
w., w.; br’., br’., outline of adjacent bracts. C.N. 18984. X 30. 
Fig. 33. Part of a sporangium containing spore-tetrads. The extremely unequal size 
of the different spores of the same tetrad is the point specially illustrated. In 
many cases (as at b) certain spores appear to be quite abortive. Ata, a mature 
spore is shown, with the 3 radiating fissures in its membrane. C.N. 1007. 
x 100. 
PLATE 82. 
Figs. 34 and 35. Calamostachys Binneyana. 
Fig. 34. Part of a sporangium containing spore-tetrads, to show abortive spores with 
normal sister-cells. In a tetrad towards the left-hand, 3 out of the 4 spores 
are abortive (b). C.N. 1011. x 100. 
A, B, C,and D. Tetrads and spores more highly magnified. 
A. A normal tetrad. All 4 spores are about equally developed. C.N. 1005. 
x 200. 
B. A tetrad in which one spore is abortive. C.N. 10134. X 200. 
C. A tetrad with one abortive spore, and one of intermediate size. C.N. 
1011. Xx 200. 
