90 MADREPORARIA 



flattened out upon a soft yielding substratum (sand or mud). The whole stock consisting of 

 a gradually diminishing series is bent about irregularly, apparently as the lower ones sank 

 regularly or irregularly into the substratum. 



The calicles are large, 6-7 mm. in diameter, very angular, and rather gaping (fig. 6), of 

 varying deptlis. Walls most frequently straight, thin, membranous, with great numbers of 

 minute perforations. Here and there the angles thicken into a stout but foaming reticulum. 

 The top edges of the walls rise to very different heights, making the whole surface not seldom 

 very irregular. The septa, as a rule, show the typical formula, and run to various heights up 

 the wall, sometimes ending in straight symmetrical rows of close delicate teeth. They are 

 most pronounced and stoutest as they run out upon the epitheca round the rim. They are 

 perforated with multitudes of the same minute pores as the walls. In the base of the fossa 

 they bend round and most of them lose themselves in the columellar tangle. The secondaries 

 in varying numbers are often very pronounced and seem to lift the columellar tangle into 

 ridges. This tangle is a close convex or raised and angular mass of delicate and foaming 

 reticulum, it is very large and unsymmetrical, not seldom running up individual septa. 



This coral has already been mentioned and compared with others which closely resemble 

 it in growth-form (p. 76, 8). Formerly the name " Goniopora Stokcsi " would have been given 

 to all Goniojwrw showing the same method of growth, but we cannot regard them as a 

 genetic group except by pretending to knowledge which we do not possess. Free stocks ou a 

 flattened circular epitheca have evidently been common in this genus, but the known forms 

 show a great diversity of calicle formation. It is jDrobable that they can arise at any time if 

 the parent polyps alight upon a soft and yielding substratum. Some of the differences in 

 calicles can be seen by comparing PI. VII. fig. 6 with PI VIII. fig. 4, and other points can be 

 gathered from the text. 



There are 11 specimens gathered from various depths and from several of the principal 

 islands of the Maldives. Together they probably form a well-marked genetic group. Four of 

 these have been presented to the British Museum by Mr. J. S. Gardiner. 



a-d. Zool. Dept. 1902. 9. 9-13. 



60. Goniopora Mauritius a)l- (PL VII. figs. 7 and 8; PI. XIII. fig. 10.) 



[Mauritius, coll. de Eobillard ; British Museum.] 



Description. — Corallum is thin and explanate, but the surface rises into blunt club-shaped 

 knobs and columns which fuse together irregularly, and occasionally fork. These columns 

 may rise 8 cm. higli, and are from 1-2 cm. thick at the base, but swell unevenly as they rise, 

 though they are not regularly moniliform. The explanate base may grow out horizontally, 

 largely free, resting on the tips of the previous growths, or creep vertically downwards or 

 upwards following the irregularities of the substratum ; 1 "5 mm. thick at the. edge, 6-7 mm. 

 thick in the older parts. 



