MATTHAI— RECENT COLONIAL ASTR^ID^ 101 



1833. Astrcea dipsacea, Quoy and Gaimard, Voy. I'Astrol., Zooph., p. 210, pi. 17, figs. 1 — 2. 



1834. Astrcea dipsacea, Ehrenberg, Corall. roth. Meer., p. 97. 



1850. Acanthastrea hirsuta, Milne Edwards and Haime, Ann. Sci. Nat., Zool., 3'= s^r., xii, p. 145. 



1850. Acanthastrea spinosa, Milne Edwards and Haime, Ann. Sci. Nat., ZooL, 3" ser., xii, p. 145. 



1850. Acanthastrea brevis, Milne Edwards and Haime, Ann. Sci. Nat., Zool., 3^ s^r., xii, p. 146. 



1850. Acanthastrea grandis, Milne Edwards and Haime, Ann. Sci. Nat., Zool., 3" ser., xii, p. 146. 



1857. Acanthastrcea hirsuta, Milne Edwards and Haime, Hist. Nat. Corall., ii, p. 502, pi. D5, fig. 4. 



1857. Acanthastrcea spinosa, Milne Edwards and Haime, Hist. Nat. Corall., ii, p. 502. 



1857. Acanthastrcea brevis, Milne Edwards and Haime, Hist. Nat. Corall., ii, p. 503. 



1857. Acanthastrcea grandis, Milne Edwards and Haime, Hist. Nat. Corall., ii, p. 504. 



1879. Acanthastrcea hirsuta, Klunzinger, Korall. Roth. Meer., ii, p. 42, pi. 5, figs. 1 and 2. 



1886. Acanthastrcea irregularis, Quelch, Reef Corals, Challenger Reports, Zool., vol. xvi, part xlvi, p. 102, 



pi. 4, figs. 2 — 2 a. 



1899. Prionastrcea hirsuta, Gardiner, Proc. Zool. Soc. London, p. 760. 



1904. Acanthastrcea hirsuta, Gardiner, Fauna Geogr. Maldives and Laccadives, p. 784, pi. 59, fig. 6. 



Corallum. Partly incrusting, partly massive. Corallites polygonal. Walls fused, 

 the inter-calicinal partitions thus formed up to 9 mm. in thickness, average about 4 mm., 

 and dense in section. Calices varying much in size, average diameters 18x13 mm. (the 

 largest calyx measuring 25x11 mm.), depth up to 15 mm., usually about 11 mm., 

 decreasing in width from calicular margins to bases. 



Septa thick, swollen in thecee, sloping, with strongly-toothed edges, almost smooth 

 sides, exsert to 2 — 3mm., 35 — 50 in number of these 13 — 18 meeting columella, with 7 — 12 

 bluntly-pointed more or less triangular hollow teeth, the first upright, swollen at its 

 base, forming the most exsert part of each septum ; teeth about 2 mm. apart at the upper 

 part, 1 mm. towards columella, the lowest tooth usually swollen. Exsert ends of septa of 

 adjacent corallites meeting in notches or alternating, hence inter-calicinal walls appearing 

 furrowed above. The broader subsidiary septa curving towards and fusing with sides of 

 principals. Columella formed of intercrossing septal teeth, mostly upright. Calicular 

 dissepiments passing from wall to columella at an angle of 45°, about 2 mm. apart. 



Multiplication by unequal fission towards calicular margins. 



Polyps. A small specimen in spirit which, on the authority of Prof Gardiner, was 

 taken from the figured example of var. megalostoma, had to be entirely decalcified, as it 

 possessed only two polyps. Owing to the lack of sufficient material and as the sectioning 

 of the two polyps was not quite successful, only a short description of the anatomy is given 

 below : Both entocoelic and exoccelic tentacles present, each with a swollen terminal 

 battery having the usual structure (most of the II h nematocysts are in their earlier 

 stages of jievelopment, the axes being very short and their nuclear origin quite apparent) 

 and up to eight sub-terminal batteries with vacuoles in their sides ; nematocysts I with 

 about 40 turns of the spiral. Tentacular endoderm vacuolated with algse scarce, hence 

 almost transparent. In vertical sections the tentacles greatly resembling those of Favia 

 doreyensis, Ed. and H. Stomodseal ridges thicker than broad, with convex inner surfaces. 

 In the larger polyp 13 principal couples of mesenteries and 23 subsidiary couples are 

 present, in the smaller polyp 12 and 5. In the stomodseal region of the polyp the ento- 

 coelic pleats thick, unconstricted at their bases, sometimes sub-divided, always close 

 together and directed obliquely towards the stomodseum, and extending to not more than 

 the middle of a principal mesentery, better developed in its outer one-third ; very narrow 



