CALCAREOUS ALGAE OF THE MIDDLE EAST 25 



In the Iraqi material Atractyliopsis is associated with very abundant Permocalculus, 

 but is itself rare. It is confined to the Darari Formation or top division of the Iraqi 

 Permian, whereas Permocalculus ranges through the whole Chia Zairi, representing 

 most of the system. It has never been seen inside Permocalculus in this material in 

 the present study. The occasional occurrence of smaller fossils within larger ones by 

 normal disturbance of randomly associated material on the sea-floor is not uncommon 

 (cf. the perfect fit of the Palaeocene codiacid Ovulites within the dasyclad Trino- 

 cladus ; PI. 23, fig. 2). With this in mind, I prefer to retain the older view of Pia 

 (1937), that Atractyliopsis represents a zone of calcified sporangial structures set 

 marginally in the dasyclad stem-cell. There is no direct proof of this for Atractyli- 

 opsis itself, but a comparable structure exists in Diplopora phanerospora Pia (Pia 

 1926), where both internal and external structures are calcified and the morphology 

 is such that accidental post-mortem fitting is impossible. 



Genus BELZUNGIA Morellet 1908 



Diagnosis. Hollow ovoid or elongate bead-like calcareous units, open at both 

 ends : the thick wall perforated by verticils of radial dichotomising and swollen 

 canals, which terminate externally as a pattern of small pores. 



Belzungia (Morellet 1908) bears the same relation to Thyrsoporella as Cymopolia 

 does to normal tubular dasyclads : that is, it possesses similar verticil-structure, 

 but is organized into separate units or bodies, united in life into a jointed branching 

 thallus, rather than the standard dasyclad single skeletal tube. Belzungia and 

 Thyrsoporella are in fact identical in the plan of their peculiar lateral branch-structure 

 within the calcareous wall-thickness. 



In the Middle East Thyrsoporella silvestrii Pfender is a common Eocene fossil. 

 Rarely, there occur isolated examples whose external morphology suggests reference 

 to Belzungia. The best example seen of this was a specimen, from the Middle Eocene 

 Pila Spi Limestone of Koi Sanjak, Erbil Liwa, Northeast Iraq. The dimensions are 

 however those of a Thyrsoporella rather than of the larger Belzungia. L. Morellet, in 

 an unpublished pioneer report of January 1931, compared a similar specimen from 

 the Palaeocene of the Sulemania district (N.E. Iraq) to the smaller of the French 

 Eocene species, B. terquemi Morellet, but the enlargement on the micrographs given 

 him was inaccurate, and measurement of the actual specimen shows that it was 

 smaller. 



Note. Part 2 of Massieux (1966b), in which this author compares Thyrsoporella 

 and Belzungia in detail, and refers T. silvestrii to Belzungia, was seen too late for 

 proper discussion in this work. However, the specimens studied in the present work 

 show the heavily-calcified walls of Belzungia, but the branch-system appears like 

 that of Thyrsoporella. 



Genus BROECKELLA L. & J. Morellet 1922 



Diagnosis (after Morellet). Hollow calcareous units, keg-shaped, traversed along 

 the axis by a tube open at the extremities. Annular cavity between the outer walls 



