74 MADREPOKARIA. 



3 cm. lonj,', on the smaller stems 2 cm. The dead portions are swathed in a continuous pelli- 

 cular epitheca like an Alveopore. 



The calicles vary greatly in size from 3-6 mm., they are rounded only on the smoother 

 parts of the stems (fig. 8). They are mostly drawn out of shape and angular (fig. 7). Of 

 varying depths, but always shallow and gaping. The walls are a beautiful open reticulum of 

 twisted flakes and threads, sometimes tliick and smooth, at others delicate and frosted. The 

 prominent septa take a very conspicuous part in the formation of the walls, and when the 

 walls appear thick it is a rising of the upper edges of the septa which gives them this appear- 

 ance ; when the calicles are flush with the surface the wall is so thin that adjacent interseptal 

 loculi communicate with one another (fig. 8). The septa are very conspicuous, the interseptal 

 loculi being open and distinct even when the sides of the septa are frosted with points. 

 The typical septal formula is visible to the naked eye ; the tertiaries are well developed and 

 bend sharply round almost at right angles, to fuse with the secondaries so as together to 

 form a trident. The columellar tangle is large, very prominent, rising like a boss of elegant 

 open reticulum in the gaping shallow calicles. From its surface the pali rise as parts of the 

 reticulum (not as single threads or flakes), and their origin from the points of fusion can 

 sometimes be seen by their outei-most portions running back along the fusing septa. 



The texture of the section of the branches shows an open, stout, coarse reticulum, without 

 trace of regular trabecule. 



There are four specimens of this coral : a, from 32 fathoms ; h, from 40 fathoms ; and 

 c and d, from 42 fathoms. The variations in size of the calicles depends apparently upon the 

 favourable conditions, for on h the dead portion of the stem shows some enormous calicles, 

 while at its tip they are all smaller again. The thickness of the skeletal elements is also 

 variable, and this makes the calicles look very different. The thin septa are frilled and 

 frosted, while the thicker are smooth and wavy. 



In the somewhat similar coral Goniopora Great Barrier Reef 12, p. 58 (PI. III. figs. 7 

 and 8), called " Rhodarcea fruticosa " by Saville-Kent, the method of growth laterally from 

 a small encrusting base is visible. This is not so clear in the present case, yet given this 

 clue to the possible method of growth, the specimens seem to fall into line, although evidently 

 more specialised for a branching growth. They all seem, for instance, as if they sloped at a 

 low angle with the horizon, and the growing tip of the largest stem has even expanded as if 

 repeating the explanate form. This kind of branching growth as a modification of an explanate 

 colony by the formation of long lateral tongues, is seen again in the genus Aheopora. There 

 is no resemblance between the Australian form and this coral, excepting in the general 

 variation in the calicles which appear here as there circular on the smooth parts, and drawn 

 out of shape on the branching tips. 



a. Zool. Dept. 93. 9. 1. 141. 



b. „ „ 89. 9. 24. 70. 

 c, d. (Parts of one and the same stock ?) ,, „ 93. 9. 1. 224. 



