CALCAREOUS ALGAE OF THE MIDDLE EAST 95 



debris, current-swept and well-rounded, and washed out some distance from the 

 organic growths which furnished it, even if to no great depth. The Cylindroporella, 

 a plant believed to be possibly somewhat similar in form to the living segmented 

 Cymopolia, owes its preservation to the relatively large, stumpy, well-calcified 

 segments surviving transport : the plants themselves would have grown on the lee 

 side of the shoals. 



In the Iraqi Cretaceous, from the base up to Albian level, dasyclad remains are not 

 uncommon and sometimes abundant. The principal genera involved are Actino- 

 porella, Cylindroporella, Munieria and Salpingoporella ; Acicularia, Acroporella, 

 Clypeina, Pianella and Triploporella also occur. The commonest non-dasyclad alga 

 is Permocalculus (see Elliott 1960 for full algal lists). Complete or near-complete 

 fossils, whether tubes, segments or verticils, are relatively uncommon and usually 

 occur in a fragmentary condition, in limy marls and argillaceous limestones. This, 

 the " debris-facies ", has been described by me (Elliott 1958a), where I interpreted it 

 as off-shore sedimentation in which fragments of littoral calcareous algae were 

 sedimented out at sea with inorganic grains of smaller size and higher specific 

 gravity. A comparison was made with modern sediments around Pacific atolls, 

 where fragmentary Halimeda and large foraminifera, roughly comparable with the 

 Cretaceous Permocalculus and Orbitolina respectively, are washed out to sea. No 

 exact analogy proved possible : the very extensive Cretaceous deposits were formed 

 on inter-orogenic shelf-seas then more widely developed than with today's post- 

 glacial submarine topography, and the wealth of Cretaceous littoral green algae 

 proliferated before the maximum, later development in the Tertiary and present-day 

 of reef-forming melobesioid algae. This debris-facies is very characteristic in the 

 Middle East, and is most typical of the Lower Cretaceous, though known elsewhere 

 from the Upper Jurassic. It occurs much more widely than remains of the littoral 

 deposits where the algal material originated. 



A completely different facies prevailed in the Upper Cretaceous of Northern Iraq. 

 Here massive limestones, of reef or shoal and fore-reef facies, with abundant rudist 

 remains, show the largely recrystallized remains of the dasyclad genera Neomeris 

 and Cymopolia. Presumably these dasyclads grew in quiet situations on and around 

 the reefs and rudist banks. In the Maestrichtian this limestone development 

 tongues eastwards into a clastic facies (transition of Aqra Limestones into Tanjero 

 Formation). As is usual with reef-structures, diagenesis has been active within the 

 main calcareous mass and the best fossils occur at the junction, as with the German 

 Upper Jurassic calcisponge and coral reefs, and the Kurdistan Maestrichtian dasyclad 

 Cymopolia anadyomenea was described from this well-preserved marginal material. 

 Within the Tanjero itself two fragmentary algae occur not infrequently ; the dasy- 

 clad Trinocladus radoicicae and the codiacid Ovulites delicatula, represented respec- 

 tively by rare broken tubes and not uncommon bead-like segments. These are 

 remains of littoral algae, sedimented not far off-shore with the sand-grains, and very 

 similar to, say, the codiacid Penicillus and the dasyclad Batophora in the Recent 

 Bahamas (Newell et al., 1959 : 224). 



Finally, the environments of the Palaeocene Dasycladaceae must be considered. 



