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176 MADREPORARIA. 



structures only visible in a few directives, the rest of the septal apparatus being that charac- 

 teristic of Montipora. On the other hand, the method of branching resulting in the stems being 

 apparently bent at sharp angles is characteristic of this genus. In the smaller piece (&) the 

 branching is very striking, and is either the result of the fusion of two stems, or else branches 

 may strike backwards, coming off from the main stem at an angle of at least 120°. 



a, b. Kandavu. H.M.S. ' Challenger.' 85. 2. 1. 11. (Type.) 



6. Anacropora spinosa. 

 Anacropora spirwsa, Rehberg, Abh. Nat. Ver. Hamburg, xii. (1892) p. 42, pi. iii. fig. 9. 



Description. — Corallum a bushy tuft of tapering stems and branches tending to grow 

 upwards, and without any marked tendency to fuse together. Height as much as 18 cm., 

 branches, at base, 1 cm. thick. The branches are curved, with spinous processes (3 to 10 mm. 

 long) brandling off at an angle of 80°. Tips of branches tend to curve backwards. 



Calicles hidden behind the spinous processes and hence not visible at first sight ; only a 

 few here and there are free and exposed ; scattered, very small, ■ 24 to 0*3 mm. ; two cycles 

 of spinous septa ; the primaries tapering toward the centre of the fossa, the secondaries for the 

 most part very feebly developed. A columeUa-like structure visible in the base of the fossa. 



In section, the ccenenchjrma is porous ; in the older part of the stem it becomes denser. 

 The surface is closely and sharply granular. 



In addition to this description. Dr. Eehberg adds that the coral partially covers by encrus- 

 tation the dead portions of its own stock, and that the colour is yellowish. In giving the size 

 of the calicles, the author wrote, " • 24 to • 30 cm.," which would certainly not be " very small." 

 I have felt justified, therefore, in changing the unit of measurement into millimetres. 



The chief claim which tliis has to be an Anacropore lies in the angular character of its 

 branching. The submerged character of the calicles, with their stunted septal apparatus, shows 

 that it undoubtedly belongs to this Montiporine subfamily. But it appears to lack most of the 

 special characters of Anacropora. Its large size, its arborescence, the absence of the protuberant 

 calicles, are against classifying it here. On the other hand, the small size of the calicles may 

 be a secondary acquirement resulting in the absence of protuberance. 



There is, unfortunately, only one specimen known, from the Pelew Islands. It is stated 

 to be preserved in the Hamburg Museum. 



