40 CALCAREOUS ALGAE OF THE MIDDLE EAST 



waning " growth suggested a half-way stage between the ordinary single tubular 

 dasyclad and the living segmented Cymopolia, but it seems much more likely that 

 the units are in fact segments themselves, as in other species, and that the frequent 

 broken pieces found are due to ordinary post-mortem mechanical fracture. The 

 number of sporangia per verticil (45-48) is high and gives a very crowded appearance 

 to this fossil in section, when compared with similarly-sized C. barbata (L.) Lmx. 

 (Recent) and C. elongata (Defr.) Mun.-Chalm. (Eocene), in both of which the count 

 is about 30. 



The flanged units give outlines of striking appearance in random thin-section. It 

 was in this condition, recrystallized in limestones, that they attracted my attention, 

 but no description was possible until material with the internal structures well- 

 preserved was discovered in the green-rock sand facies of the same age. In Tibet, 

 the Cymopolia sp. of Morellet (1916 : 49; Maestrichtian of Kampa Dzong) may 

 possibly be this species, as C. tibetica Morellet is associated with C. anadyomenea in 

 Iraq. 



Although C. anadyomenea is thus distinctive for the Maestrichtian, an apparent 

 homoeomorph occurs in the Lower Cretaceous of Italy (Praturlon 1964). This is not 

 yet fully described due to scarcity of material, though it appears to differ in flange- 

 profile. This or a similar species occurs also in the Lower Cretaceous of Borneo (Bau 

 Formation), and in the Lower Cretaceous of Jugoslavia (Radoicic in Hit.). 



Cymopolia eochoristosporica sp. nov. 

 (PI. 9, figs. 1-3) 



Description. Tubular cylindrical thickwalled units of about 2-0-2-2 mm. 

 external diameter (maximum seen 2-42 mm.), internal diameters 0-73-0-86 mm. 

 (maximum seen 0-91 mm.), giving a d/D ratio of 36-40%. Estimated lengths of 

 units up to 9 or 10 mm. Verticils of 12-14 primary branches which are probably 

 inclined upwards at a low angle from the horizontal. Each branch communicates 

 with the stem-cell by a very short connecting pore of 0-03-0-04 mm. diameter. 

 These pores are set about 0-26 mm. apart measured (vertically) along the stem-cell 

 walls. The branch then expands into the main swollen portion, seen as rounded- 

 rectangular in near-vertical section, where it measures 0-390-0-416 mm. radially 

 and 0-234 mm - vertically. These swollen portions occupy much of the thickness of 

 the walls and are thus very close-set, the interstices being only 0-030 mm. thick. 

 Finally each swollen portion divides into a small cymopoliform cluster of one 

 spherical sporangium and four divergent secondary sterile branches. Diameter of 

 the sporangium is 0-13 mm. ; and the diameter of the short neck or pore connecting 

 it with the swollen primary is 0-052-0-065 mm. The secondaries have a median 

 diameter of 0-040-0-052 mm. and expand terminally at the outer surface to shallow 

 depressions of about 0-104 mm - diameter. 



Horizon. Maestrichtian of Trucial Oman, Arabia. 



Holotype. The specimen figured in pi. 9, figs. 1, 2 from the subsurface Aruma 



