CALCAREOUS ALGAE OF THE MIDDLE EAST 65 



by a tuft of narrow sterile branches, we do not know whether these simple-branched 

 late Palaeozoic dasyclads were similar in this respect. The fossil is presumably not 

 to be regarded as a new small species of Eogoniolina Endo, which has no distal 

 aperture ; its branches are not those of Gyroporella, and it is smaller and with 

 different shaped thallus than the somewhat doubtful Pseudogyroporella (Endo 1959). 

 Although segments of Mizzia spp. auct. vary considerably, the fossil under discussion 

 is outside the known range of segment-shape for this genus. It is moreover rare 

 amongst an abundance of Mizzia, and the calcareous traces in the stem-cell cavity, 

 never seen in any of very many Mima-segments examined, suggest a different 

 internal organisation. It seems best to admit that its exact place amongst the 

 dasyclads is at present obscure, and to describe it as a new genus, tentatively 

 referable to the tribe Diploporeae. 



Genus PIANELLA Radoicic 1962 



Diagnosis. Calcified cylindrical dasyclad tube showing successive verticils of 

 horizontally directed branches, alternating in position from one whorl to the next : 

 branches simple, unbranched, widening evenly outwards from a narrow insertion at 

 the stem-cell cavity to the anterior : i.e. differing only from Macroporella in the 

 regular verticillate, instead of irregular, insertion of the branches at the stem-cell. 



Pianella gigantea (Carozzi) Radoicic 



1955a Macroporella gigantea Carozzi : 43, pi. 6, fig. 4 ; text-fig. 7. 



i960 Macroporella gigantea Carozzi ; Elliott: 221. 



1962 Pianella gigantea (Carozzi) Radoicic ; Radoicic : 202. 



Description (based on Carozzi). Calcified cylindrical dasyclad tube of 1-2-1-75 

 mm. external diameter, internal diameter 66-70% of corresponding external diameter; 

 successive verticils of horizontally directed branches, 30-40 per verticil, widening 

 from 0-03 mm. diameter internally to 0-09-0-20 mm. externally to give a regular 

 external pattern of polygonal pores. 



Horizon. Upper Jurassic of Europe (Switzerland) and Arabia (Oman, Hadhra- 

 maut). 



Material. Upper Jurassic of Jebel Kaur, Oman ; also in derived Upper 

 Jurassic in the Upper Cretaceous Hawasina-complex at Jebel Buwaida, Ibri, Oman. 

 Fragmentary remains in Upper Jurassic of the Jebel Laut area, Wahidi State, 

 Hadhramaut, and see also Hadhramaut record of Beydoun (i960 : 140). 



Remarks. Carozzi described his species from the Sequanian-Portlandian of the 

 Swiss Upper Jurassic. Associated fossils and stratigraphy suggest the upper part of 

 the Upper Jurassic for the Middle East occurrences also. The species is apparently 

 uncommon there and remains are fragmentary or poorly preserved. Praturlon 

 (1966) relegates this species as a synonym of P. pygmaea (large individuals). 



