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MARINE BIOLOGY OE THE SUDANESE RED SEA. 



There arc no nutritive canals in the axis. A longitudinal section shows 

 that the axis is built up of minute spindle-shaped spicules, fused together, 

 and arranoed with their long axes in the line of the long axis of the 

 ))ranch. 



The nodes are much shorter than the internodes (3-4 mm.) and are some- 

 what thicker. They are composed of a dark-red horny substance, which, 

 under the microscope, appears as a yellowish network with numerous red 

 spindle-shaped spicules in the meshes. 



It occasionally happens that a branch arises from an vntemode ; in such 

 cases the first joint is horny. 



The cream-coloured coenenchyuia is crowded with small sjiicules. Blost of 

 these are white, but some are tinged with yellow or yellowish green. Spiny 

 clubs and more warty double-clubs and dumb-bells are very abundant. 

 Spindles bearing numerous very minute warts are less common, and simple 

 spindles are rare. 



The following measurements were taken pf length and breadth in milli- 

 metres : — • 



Clubs: 0-13GX 0-084; 0-153 x 0059; 0-119x0 051. 



Double clubs: 0-012 x 0-034: 0-067x0055; 0-051x0042. 



Spindles: 0-187 xO'Ool; 0-119x0 025. 



Red spindles of nodes • 0-102 x 0-017; 0-085 x 0-017; 0-0G8 x 0-002. 



The small polj-ps are spirally arranged almost uniformly all round the 

 branches. They are nearly all retracted, lying almost Hush with the surface 

 of the ccenenchyma. Besides the substantial anastomosis, there niay be a 

 more superficial fusion of ccenenchyma when one branch lies against another, 



iocaK<j/.-^CoraUrcef, Mersa Makdah, Shubuk. 



Clathraria acuta, Gray. (Plate 7. figs. 3 & 4.) 

 See Gray: Catalogue of the Lithophytes in the British Museum, 1870, p. 12. 



This species is represented by two specimens, one of 7 cm. and the other of 

 5 cm. in height. The mode of growth is tree-like and graceful. The 

 branches, much more slender than in C. ruhrinodis, are cylindrical and of 

 very uniform width until close to their end, when they narrow abruptlv into 

 a sharp apex. 



In the larger specimen there is a main stem, which gives off two long 

 branches on one side, two long and three short on the other, and then bifur- 

 cates at the top. The side branches also show dichotomy. Of the seven 

 branches four arise from the internodes. The other specimen is branched 

 dichotomou.sly throughout and the branches arise from the nodes. On the 

 whole the branching is in one plane. There may be fusion of branches, but 

 not nearly to the same extent as in C. ruhrinodis. 



The colour of the preserved speciinens is a delicate flesh-pink, marked bv 



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