CALCAREOUS ALGAE OF THE MIDDLE EAST 61 



(Fritsch 1935 : 388). If fossilized this structure would give a very thin cylindrical 

 test perforated by alternating pores. If however calcification were to develop 

 further outwards between the swelling primaries, wedge-shaped interstices would 

 develop, but much closer than in Pagodaporella. Since dasyclad branches are norm- 

 ally thin at the points of origin and then swell out, it may be that Pagodaporella was 

 like Dasycladus but with fewer, thicker branches, and that a thickened fleshy stem- 

 cell wall bulged outwardly rather than inwardly between branches and was then 

 calcified more heavily than in Dasycladus. (Fig. 4). If this were so the Pagoda- 

 porella skeleton would represent the calcification between swelling primaries, but 

 separated from the level of their points of insertion by the thickness of the externally 

 intermittently swollen stem-cell wall. In this way the present internal cavity of the 

 fossil would be a record of the maximum diameters of the stem-cell, and the thin 

 points of insertion of the primaries would have been some little distance inside the 

 cavity. 



Pagodaporella is therefore tentatively referred to the Dasycladeae : we know that 

 branched choristospore laterals, seen in living genera of the tribe, had already 

 evolved by the Palaeocene from the evidence of heavily calcified genera, e.g. Cymo- 

 polia. This structure may well have been present in Pagodaporella, even if no 

 calcified evidence remains, and it may be that the genus is ancestral to the living 

 Dasycladus : reduction of calcification and increase in number of branches seems a 

 likely evolutionary trend. 



Genus PALAEODASYCLADUS Pia 1927 

 {PALAEOCLADUS Pia 1920 non Ettingshausen 1885) 



Diagnosis. Elongate near-cylindrical club-shaped calcified dasyclad, showing 

 numerous successive verticils of strongly-inclined branches : the branches show 

 primaries, dividing into clusters of four to six secondaries, in turn dividing into 

 clusters of four to six tertiaries. All branch-segments slightly swollen : successive 

 verticils show a progressive elaboration of branch-detail. 



Palaeodasycladus mediterraneus Pia 



(PL 16) 



1920 Palaeocladus mediterraneus Pia : 118, pi. 6, figs. 1-5 ; text-fig. 22. 



1927 Palaeodasycladus mediterraneus Pia : in Hirmer's " Handbuch der Palaobotanik ", Bd.i 



79- 

 i960 Palaeodasycladus mediterraneus Pia ; Elliott : 221. 



Description (from Middle East material). Near-cylindrical elongate club-shaped 

 dasyclad, length 7-8 mm. or more, external diameter increasing slowly and regularly 

 from 1 mm. or a little less at the base to about 2-4 mm. in the terminal expansion, 

 internal diameter from about 50% of corresponding external measurement at the 

 base to about 30% or less at the terminal expansion i.e. the stem-cell cavity diameter 

 increases only slowly compared to the external measurement. Close-set successive 

 verticils of branches, 5 or 6 per mm. of measured length in mid-thallus : each verticil 



