MATTHAI— RECENT COLONIAL ASTR^ID^ 111 



1904. Acaiithastroea hirsuta var. microstoma, Gardiner, Fauna and Geogr. Maldives and Laccadives, ii, p. 784, 

 pi. lix, fig. 6. 



Oorallum. Usually incrusting, flat or convex, tending to become massive. Corallites 

 hexa- or pentagonal, sometimes meandering (two or three corallites in a row being without 

 intervening partitions). Inter-calicinal walls 1 — 5 mm. in thickness, average about 

 2 "5 or 3 mm. Calices with average diameters 1 2 and 8 mm. (the longest meandering 

 calyx being 25 mm.), depth 7 or 8 mm. 



Septa usually sloping, swollen towards walls, those of adjacent corallites continuous 

 over inter-calicinal walls, with conspicuously toothed edges, sides usually smooth, some- 

 times rough. Septa up to 45 in number, average about 35 ; of these 12 — 18 meeting 

 columella, each with 6 — 8 smooth pointed teeth (hollow or solid), towards calicular 

 opening usually becoming longer, obliquely directed and swollen at their bases, the first 

 tooth (situated over the inter-calicinal wall) being longest (up to 3 mm.) and vertical and 

 forming the most exsert part of each septum ; between two such rows of teeth the inter- 

 calicinal partition appearing furrowed. Subsidiary septa often curving towards and 

 fusing with sides of principal septa in groups of up to 3 or 4 as in F. complanata. 

 Sometimes a few alternating rudimentary septa but the cycle never complete. Columella 

 formed of interlacing septal teeth, often with points above, ^ — |- width of calyx. 



Multiplication by unequal or equal fission, rarely by marginal fission. 



I apply the name Favia hemprichii to this species with some hesitation, as Ehren- 

 berg's type of Astrcea hemprichii is a small incrusting specimen measuring 9'5 x 8"5cm. 

 (PI. 36, fig. 3). Judging only from the corallum, the grouping of my specimens 

 under Ehrenberg's species appears to be the most satisfactory. Perhaps they resemble 

 Klunzinger's type (8"5 x 7 x 4 x 4 cm.) of Prionastrcea spinosa somewhat more than Ehren- 

 berg's example, but the former is in no essential respect different from the latter ; it has 

 polygonal corallites, well developed columellse, conspicuous septal teeth which are longer 

 and erect on the exsert septal ends, and its main septa are continuous over the walls. 



This species is closely related to F. complanata, having more or less the same facies 

 as the edge-regions of the latter, but differs from it in (1) the corallum being flat or convex, 

 without the hillocky mode of growth so characteristic of F. complanata, (2) the corallites 

 more uniform in shape and size, (3) fission sub-equal or equal, rarely marginal, (4) the 

 general absence of smaller exsert ends alternating with those of the main septa, (3) the 

 teeth being smooth and pointed and on the whole more conspicuous, increasing in length 

 towards the calicular opening, hence the corallum appearing more thorny. The actual 

 relationship of these two species can be settled only after a comparative study of their 

 polyps. 



Owing to the swollen nature of the septa in the theca and of the teeth, the species 

 also resembles F. hirsuta. However the specimen, which Gardiner referred to Acantha- 

 strcBa hirsuta var. microstom,a (Klunz.) (PL 27, fig. 4) appears to be more related to the 

 present species than to var. megalostoma, its calices being much smaller than in the latter 

 and of almost uniform size (diameters about 10 and 8*5 mm., depth 7 or 8 mm.), the 

 inter-calicinal walls thinner (about 2'5 mm.) and the septa less in number (30 — 35). The 

 specimen serves to show the degree of thickness possible in this species. The specimens 



