MATTHAI— RECENT COLONIAL ASTR^ID^ 75 



and polygonal, the calices being 2 — 2"5 mm. in diameter. In every corallite about 12 septa 

 meet the columella, each usually with a conspicuous paliform lobe ; six (secondary septa) 

 of these septa are somewhat thinner than and alternate with the others (primary 

 septa) ; an alternating cycle of twelve narrower septa (tertiaries) is present. The 

 columellse are unique in being quite solid rods — it would be interesting to see if the 

 columella arises as such from the basal plate — which are either circular in outline or 

 somewhat laterally compressed and rough at their upper ends. New corallites appear to 

 arise by true budding. 



There are two more examples of this species in the Paris Museum, one of which is 

 from St Thomas (Duchassaing). The types of Milne Edwards and Haime's two remaining 

 recent species of Stephanoccenia, viz. S. michelini and S. dendroidea, are missing. 



Esper's figures (p. 99, PL 79) of Madrepora intersepta are not adequate for satisfactory 

 comparison with Milne Edwards and Haime's types. 



When polyps are examined Stephanoccenia may, in all probability, prove to be a good 

 genus. Its nearest ally appears to be Leptastrea. 



2. Heliastroea cavernosa (Esper); Ed. and H., Coi'all. ii., p. 463. 

 Heliastrcea gigas, Ed. and H., Corall. ii., p. 458. 



In the Paris Museum are four large specimens and two small ones from " mers 

 d'Amerique," referred by Milne Ed\A'ards and Haime to Heliastrcea cavernosa. In these 

 the corallites are circular, projecting more and further apart than in Heliastrcea conferata, 

 Ed. and H. (hence the costse are better seen), their walls increasing in thickness fi:om the 

 corallite-margins towards the peritheca. The calices are 7 or 8 mm. in diameter ; usually 

 24 septa meet the columella in every corallite ; alternating with these is a cycle of 

 narrower septa. The columellse are well developed, being ^ — -^ the width of the calices 

 and formed of septal trabeculae. The costse are alternately large and small, corresponding 

 to the two septal cycles, those of the neighbouring corallites usually meeting in notches. 

 The peritheca is highly vesicular and tends to break down ; thus the corallum approaches 

 the conditions in Diploastrea heliopora ; when the peritheca is entirely removed, the 

 corallites appear as long cylinders. 



There are three more specimens with the same name, but they are quite small and 

 much rubbed. 



There is no doubt that Milne Edwards and Haime's examples are identical with 

 Esper's figure of Madrepora cavernosa (p. 18, PL 37). They have also a certain 

 resemblance to one of my specimens (no. 13) of Echinopora gemmacea (Lam.). 



The only example of Heliastroea gigas in the Paris Museum has only two sectioned 

 corallites, resembling those of Heliastrcea cavernosa. 



3. Explanaria argus, Ehrb., Corall. ii,, p. 83 [non Astrea argus, Lam., which is 

 Heliastrcea cavernosa (Esper)]. 



Heliastraia conferata, Ed. and H., CoralL ii., p. 460. 

 Heliastrcea lamarckana, Ed. and H., Corall. ii., p. 465. 



Of Milne Edwards and Haime's examples of Heliastrcea conferata (locality unknown) 



10—2 



