CALCAREOUS ALGAE OF THE MIDDLE EAST 37 



with whorls of infertile primary branch-canals. These are normally at right angles 

 to the longitudinal axis, and each divides terminally into secondaries. Sporangia 

 and infertile branches alternate in position in successive whorls. 



Cylindroporella is a distinctive Mesozoic dasyclad first described by Johnson 

 (1954b) : type-species C. barnesii from the Albian Edwards Limestone of Texas. 

 Elliott (1957) described new species from both Upper Jurassic and Lower Cretaceous 

 of the Middle East, and has since recognized C. barnesii there. The Jurassic species 

 C. texana Johnson (1961a) and C. ellenbergeri Lebouche & Lemoine (1963), and the 

 Upper Cretaceous C. elassonos (Johnson & Kaska, 1965), have not yet been identified 

 from the Middle East. 



Cylindroporella barnesii Johnson 

 (PI. 6, figs. 3, 4) 



1954 Cylindroporella barnesii Johnson : 788, pi. 93, figs. 1-7. 



Description. The characters of this, the type-species, are those of the genus. 

 The table below gives the various measurements by which the three species recog- 

 nized in the Middle East may be distinguished. 



Horizon. Albian of Texas : Lower Cretaceous of Iraq. 



Material. Fragmentary material referable to this species has now been recog- 

 nized from two localities in Iraq : from the subsurface Garagu Formation (Valan- 

 ginian-Hauterivian) of Makhul no. 2 well, Mosul Liwa, and from the Sarmord 

 Formation (about Aptian level) at Sekhaniyan, Surdash, Sulemania Liwa. 



Remarks. Both the above occurrences show a Cylindroporella with outer 

 diameter of 0-468 mm., inner diameter 0-156 mm., and sporangial diameter of 0-156 

 mm. ; they are distinct from the larger C. sugdeni Elliott, which they overlap in 

 range, and seem best referred to the type-species, described from the Albian. 



Detail of Cylindroporella spp. (M.E.). Dimensions (in mm.) 



Length of segment 

 Diameter of segment 

 Diameter of central canal 



Diameter of sporangia 



Number of sporangia per whorl Usually 6 in all three species 



Number of sterile branches per whorl Usually 6 in all three species 



Angle of branches to stem 90 ° in all three species 



Number of terminal secondary branches Probably 4 in all three species 



Vertical distance between whorls 0-13 01 7-0 -187 0-39 



arabica 



barnesii 



sugdeni 



i'43 



2-8-5-1 



3-o + 



o-3i-o-57 



0-38-0-55 



0-78-1 14 



variable ; 



0-08-0-15 



0-234-0-36 



0-052-0-230 







0-078-0-156 



0-134-0-189 



0-26-0-312 



