50 MADREPOUARIA. 



Calicles very irregular in size, up to 2 • 5 mm., angular and thin walled in the valleys 

 between the lobes, but deep, round, and funnel-shaped, or cylindrical, on the smooth round 

 tops of the loljes (see PI. II. fig. 2), round and shallow at the sides (see PI. II. fig. 3). The walls 

 are thin and built of stout palisades between the crowded angular calicles, but thick, round- 

 topped, and reticular between the deep calicles ; broad, up to 2 mm., flat and granular, with a 

 faint median furrow between the shallowest lateral calicles. Twenty-four septa striate the 

 thicker walls, rising above them as plates and projecting into the calicle as short sharp points, 

 which descend vertically as straight, sharp, but slight and interrupted ridges into the fossa. 

 The tertiaries soon become rudimentary. The primaries (and ? some of the secondaries) project 

 suddenly as thin delicate plates, from which small knobs, sometimes thin plates or plate-like 

 teeth, arise in the fossa to a variable height, sometimes remaining deep down, to form the pali. 

 In the lateral calicles these become stout frosted granules. In these shallow calicles the flat 

 wall appears solid, its broad top is covered with rows of fiosted granules, corresponding to the 

 two sets of septa. The coral is very tough and heavy. 



The single specimen, 10 cm. long and 9 cm. high, is interesting because its growth-form 

 is imique in this genus. Its chief structural features are, the slightly exsert septa shown in 

 fig. 2 (PI. II.), which change into the broad flat wall shown in fig. 3. The median furrow here 

 shown is rare in this genus. 



The deep calicles at the top, changing into the primitive type at the sides, show that it 

 owes its massive form and rounded top to the lengthening of the central calicles. 



An outgrowth from one of the free edges shows what the early stage of the colony may 

 have been (see fig. 10, PI. XL). The centre is raised and the edges are rapidly expanding, 

 with a zone of small buds. This, as stated, is not really a young colony but arose as an 

 outgrowth from the larger stock, and has the free edges of similar outgrowths under it. 



a. Zooh Dept. 92. 12. 1. 162. 



17. Goniopora Great Barrier Reef (i2)3. (PI. II. fig. 4; PI. XL fig. 11.) 

 [ ? Exact locality, coll. Saville-Kent ; British Museimi.] 



Descnption. — Corallum round pear-shaped, enveloping the tops of other corals, which it 

 closely encrusts, the lower edges of the living layer creeping under into all the crevices and 

 open spaces. An epitheca appears under the creeping edges, and sometimes bending up on to 

 them as a pellicular covering. 



CaUcles neatly rounded like deep cylindrical punctures, variable in size up to about 

 3 • 5 mm. across and about 3 mm. deep. Walls vertical, and where thin, i.e. on the top of the 

 stock, very fi'iable and fenestrated, as if built up of rows of jagged trabeculffi very sparsely 

 joined into a zigzag, making the rims ragged and irregularly denticulate. Nearer the sides 

 the walls thicken and the septa show across their tops. They still, however, remain very open 

 and friable, but become more solid still lower down, where indications even of a double row 



