192 



PEOF. P. MAETm DUNCAN S REVISION OF THE 



usually veiy different on the base. Corallites small, wide apart, 

 separated by coenencliyma in which they are immersed, or else the 

 calicular margin is raised, lacerate, and spinulose. Calices deep, 

 with columella and pali. Septa little developed, six or twelve, 

 and often trabecular. Secondaries smaller than the primaries. 

 Distribution, — Recent. Eed Sea, Indian Ocean, Pacific. 



Mr. S. O.Eidley has investigated and described a very interest- 

 ing form, which he places in a new genus, Anacropora. The 

 aspect of the species is that of one of the Madreporidse, and the 

 two large primaries add to this character ; but the gemmation 

 differs. The septa are trabecular, but are fairly developed. 



Grenus Anacropora, Bidley, Ann. Sf Mag. Nat, Hist. ser. 5, 

 vol. xiii. p. 287 (1884). 



Colony ramose. Axis and apex of branches formed by a spongy 

 coenenchyma. New calicles formed centripetally, i. e. from the 

 base towards the apex; no calicle of any kind at the apex. 

 Calicles equally distributed all round stem and branches, wdth a 

 tendency to arrangement in longitudinal series. Septa trabe- 

 culate, comprising two cycles of six septa each, two (approxi- 

 mately upper and lower) primaries being larger than the four 

 lateral primaries. 



Distribution. — Recent. Keeling Islands. 



The proper position of Rsammocora is with the Lophoserinse, 

 p. 161. I have only been able to study this genus after going to 

 press. 



Genus Psammocora, Dana^ Zooph. Wilkes Eocped. (1846), 

 p. 344, amended. 



Colony in ramose tufts ; braiichlets often lobed, or in convex masses, or 

 foliated and lobed. Surface more or less irregular, from gibbous humps or 

 linear elevations. Coenenchyma exists in places, especially on the gib- 

 bosities, which, however, just as frequently are covered with calices. 

 Calices small, centres distinct, but margins ill-defined, usually circular, 

 shallow, with a small central fossa with a minute papilla, the top of the 

 columella. Septa 6-9-12 in number, very variable in thickness ; some- 

 times one half of them reach the columellary space, and form a ring of 

 tissue around the columella, the other septa having previously united to 

 them ; or several septa are club- or boss-shaped at their free margins, and 

 are much larger than the others which environ them. These larger septa 



