6o 



CALCAREOUS ALGAE OF THE MIDDLE EAST 



(Palaeocene) of Bekhme, Erbil Liwa ; thin-section material from the Sinjar Forma- 

 tion (Palaeocene-Lower Eocene) of Banik, Mosul Liwa, and from the Kolosh Forma- 

 tion (Palaeocene-Lower Eocene) of Sedelan, Sulemania Liwa ; all in northern Iraq. 



Remarks. Pagodaporella is the fossil record of a little, thick- branched dasyclad 

 which calcified only near the stem-cell, at the base of the branches, no traces being 

 left of branch-structure nor of sporangia : its relationships are therefore uncertain. 

 The peculiar thin-section appearance, with more gaps than skeleton, was known for 

 some time before the discovery of solid specimens, which when sectioned led to the 

 elucidation of the random sections. 



The living Dasycladus (D. clavaeformis (Roth) Ag. ; Mediterranean) shows a 

 comparable limited calcification which is however not identical. Here each verticil 

 shows 10-15 branches, branched outwardly to the third degree and also bearing 

 sporangia : the primaries narrow markedly at their inner junctions with the stem- 

 cell, and between their points of insertion the fleshy stem-cell wall is markedly 

 thickened inwardly, within the stem-cell itself, and thinly calcified externally. 



Fig. 4. Diagrammatic transverse sections of Dasycladus (above) and Pagodaporella (below, 

 hypothetical). Greatly enlarged, X 150 approx. Spaced stipple, plant tissue ; close 

 stipple, thickened portions of stem-cell wall ; black, calcareous structure. Each 

 section shows half the stem-cell with branches attached. The reconstruction for 

 Pagodaporella explains the possible origin of the structure found fossil. 



