CALCAREOUS ALGAE OF THE MIDDLE EAST 39 



terminally rounded ; in each the main longitudinal canal (stem-cell cavity) extends 

 from end to end, the wall-thickness perforated by close-set more or less horizontal 

 whorls or verticils of branch-canals. Each verticil consisting of several branch- 

 systems of the same pattern : an inner primary branch dividing into several (usually 

 four) secondaries, and one sporangial cavity, usually spherical : the secondaries 

 reach the outer surface to give a dense pore-pattern. 



The dasyclad Cymopolia is well-known from living species in the warm waters of 

 the East and West Indies. The plant shows a branched thallus of conventional 

 " seaweed " pattern, in which the fronds are composed of heavily calcified serial or 

 consecutive units, united by non-calcified tissue : each of these units corresponds in 

 general plan to the single calcified tubes of the more normal dasyclad genera. After 

 death the units come apart, and it is in this condition that they are met with in the 

 fossil state, being known thus from the Upper Cretaceous onwards. 



Cymopolia anadyomenea Elliott 

 (PI. 7 ; PI. 8, figs. 1, 5) 



1 959 Cymopolia anadyomenea Elliott : 218, pi. 1, figs. 1-4, 8. 



Description. Elongate hollow tubular units each showing several external 

 horizontal annular flange-like swellings or increases of diameter, more or less regularly 

 spaced, varying in development in different individuals : external surface finely 

 patterned with small closely-set pores. Length (incomplete), up to 6 mm. seen ; 

 diameter varying both with absolute size and relative flange-development, 1-5- 

 3-9 mm. (usually 2-0-2-5 mm.). Internal diameter of the main cell-cavity either 

 constant or variable : if the latter, waxing and waning to correspond with external 

 diameter-changes, but to a lesser extent. The d/D ratio varies correspondingly from 

 50-70%, being almost always 50% or more : only with extreme external flange- 

 development can a figure of less than 50% be obtained. The wall-thickness is 

 perforated by numerous closely-set whorls or verticils of crowded branches, 45-48 

 per verticil, and about 6 verticils per 1 mm. measured vertically. Each primary 

 branch gives rise to a globular sporangium of 0-05-0-08 mm. diameter and four or 

 more secondary branches set at an angle of 45-60 ° from the horizontal. The branch- 

 systems are coarser at flange-levels, where the diameters of primary and secondary 

 branches were 0-065 mm - an d 0-039 mm - on a large specimen, and 0-039 mm. and 

 0-026 mm. on a small specimen. 



Horizon. Maestrichtian of Northern Iraq and Afghanistan ; possibly from 

 Maestrichtian of Tibet. 



Material. Upper Aqra Formation (Maestrichtian) of Aqra and of Chalki Islam, 

 Hadiena Formation of Chalki (top Senonian), Upper Bekhme Formation (Maestrich- 

 tian) of Chia Gara, and Aqra-Bekhme Formation of Gal-i-Mazurka, all five limestone 

 localities in Mosul Liwa. Also in the green-rock sands (Tanjero Formation, Maes- 

 trichtian) of Diza, Erbil Liwa. 



Remarks. This Cymopolia may be distinguished from other species of the genus 

 by the peculiar annular flanging of the calcareous units. This " waxing-and 



