MADREPORARIA. 761 



is less difference in the two classes than in any of the present collection, though all the 

 characters of the latter vary considerably in different parts of the colonies. The two classes 

 of septa may alternate with one another in any series, or the larger septa may be separated 

 by an average, in parts even of the same colonies, of 2, 3 up to 8 smaller septa. On opposite 

 sides of the walls the septa may lie against one another but more frequently alternate to 

 some degree ; the larger septa throughout are much more frequently arranged contiguous to 

 the smaller, but there is every variation. The septa range from G — 10 in 1 cm. ; the series 

 are 15 — 3 cm. wide by 1 — 2 cm. deep. The longitudinal septa joining calicular centres range 

 from 1 — 5 in number. 



The specimens undoubtedly belong to Symjjhyllia sinuosa, of which S. grandis appears 

 to me to be only a vigorously growing form, though Ed. and H.'s figure is peculiar. The 

 descriptions (no figures) of 8. agaricia, radians, and valenciennesi are not suflicient to 

 separate them, though they may be really different species. The same remark applies to 

 S. subtilis, Rehberg (Abth. Nat. Ver., Hamburg, Bd xii. p. 16, PI. I. fig. 6, 1892). 



Locality. The species is fairly common on the lagoon shoals and reefs of the Maldives. 

 I have also seen it in the outer slope, and it is not improbably in places an imjjortant reef- 

 builder. The specimens come from Hulule, Goidu and Minikoi. Colour of the Minikoi 

 specimen (fig. 4), a large mass several feet in diameter, in central upper part of the colony, 

 over walls transparent, peristome very light green dotted with dark gi-een, edge of stomodoeum 

 white, and at sides, over walls very dark green, peristome white slate, edge of stomodoeum 

 white. 



VIII. Genus Coeloria. 



Ed. and H., ii. p. 411; Klz., p. 1.5, and Gard., p. 740. Ulophyllia, Ed. and H., ii. p. 377; 

 and Quelch, Beport on the Reef Corals of H.M.S. Challenger, p. 88 (1886). 



I still consider that Coeloria and Maeandrina are quite separate genera, the latter 

 having, so far as we know, a true columella, and the former merely trabeculae extending out 

 from the septa to fill up the axial fossa. The species appear to me to fall into three types, 

 which may be best indicated by C. pachychila, daedalea, and magna. C. cooperi shows a 

 transition to the last, which would formerly have been j)laced in the genus Ulophyllia. The 

 regular method of division of the series, or of the circumscribing of the calices in the genus, 

 is by the enlargement and fusion of septa from their two walls or ridges. The septa on either 

 side in their further growth bend away from the new walls, thus removing to some distance 

 the columellar trabeculae, to which the septa give rise. Later, the new walls themselves get 

 septa, and form the end walls of series or the circumscribing walls of calices. The first part 

 of this process takes place very early in Ulophyllia, but it is no different to what occurs 

 in Coeloria, and the gap between the species of the two genera — if there was any before — 

 is bridged by C. cooperi and magna as well as the Challenger species. Ulophyllia is 

 undoubtedly, so for as its recent species are concerned, a synonym of Coeloria. 



Distribution. The genus is the most abundant of all Astraeids on the reef-flat and 

 outside the edge of the reef to 5 f, where the immediate force of the breakers is felt. It also 

 occurs abundantly on the outer slope down to 15 /". and one specimen comes from 28/! It 

 may be found occasionally on the sand flat behind the boulder zone, but it evidently loves 

 neither this position nor shoals in enclosed lagoons. Colour, generally some shade of green. 



