MATTHAI— RECENT COLONIAL ASTR^ID^ 109 



trabeculsB ; but the coralHtes are much larger than in F. abdita, the septa thicker and 

 further apart, and the alternating septa meet their fellows over the walls and not the 

 main septa of the adjacent corallites. 



Klunzinger's var. superficialis (PI. 4, fig. 8, type measuring 9x5'5x5cm.) has 

 shallow corallites about twice as long as broad, average diameters 20 and 10 mm., inter- 

 calicinal walls and septa thicker, and the columellse either rudimentary or absent. This 

 variety approaches Favia hirsuta (Ed. and H.) in the following respects: (l) heavy 

 corallum, presenting a similar appearance in transverse section, (2) the inter-calicinal 

 walls, septa and septal teeth thickened but not to the same extent (septal sides almost 

 smooth), (3) the corallites with similar shape, being widest at the calicular openings and 

 gradually narrowing towards the bases. Resembling Klunzinger's type is one of my 

 specimens from Egmont, Chagos, measuring 23x13x11 cm. (PL 27, fig. 3), but in the 

 latter the columellse are well formed, of twisted septal trabeculse. 



Klunzinger's var. ohtusa of Goniastrwa halicora (type measuring 18x10x4 cm.) 

 has the same facias as his Prionastrcea vasta (PL iv, fig. 12), but has a somewhat thinner 

 build and smaller corallites. Resembling this type are two of my specimens, with 

 incrusting coralla : one from Aldabra (ll'5xl0'5 cm., PL 27, fig. 6), which has thin 

 sharp-ridged inter-calicinal partitions (not more than 1 mm. in thickness), calices about 

 15 X 10 mm. wide by 8 or 9 mm. deep, with more or less distinct pali-crowns ; the other, 

 from Salomon, smaller, but with thicker walls and septa. 



In the Paris Museum are two large specimens of Prionastrcea vasta, Klunz., from 

 Koseir, representing Klunzinger's two varieties, and also a good example of Goniastrcea 

 halicora var. ohtusa from the same locality. 



Localities. Chagos: Salomon (3) ; Egmont (1). Aldabra (l). Previously recorded 

 only from the Red Sea. 



18. Favia gomplanata, Ehrenberg. (PL 30, figs. 1 — 3.) 



1834. Favia complanata, Ehrenberg, Corall. roth. Meer., p. 93. 



1834. AstrcBa tesserifera, Ehrenberg, Corall. roth. Meer., p. 97. 



? 1846. Astraa tesserifera, Dana, Expl. exp. Zooph., p. 248, pi. 13, fig. 9. 



1850. Prionastrea michelini, Milne Edwards and Haime, Ann. Soi. Nat., Zool., 3" ser., xii, p. 132. 



1851. Prionastrea tesserifera, Milne Edwards and Haime, Pol. fo.ss. terr. palseoz., etc., p. 102. 

 1857. Prionastrcea tesserifera, Milne Edwards and Haime, Hist. Nat. Corall., ii, p. 517. 

 1879. Prionasfaa tesserifera, Klnnzinger, Korall. Roth. Meer., iii, p. 37, pi, 4, fig. 9. 



Corallum. Incrusting, following irregularities on surface of attachment, often rising 

 into hillocks, which usually end in ridges with corallites on either side of each such ridge 

 from light to heavy, and with a thorny appearance, generally distorted. Corallites polygonal, 

 on the hillocks, with one side much higher than the other, in the narrow valleys with 

 a tendency to be drawn out, more regular in shape on the level regions. Inter-calicinal 

 walls varying from very thin and sharp to 5 or 6 mm. broad. Calices with diameters up 

 to 18 by 12 mm., depth up to 10 mm. 



Septa varying considerably in thickness, sloping or with their upper two-thirds 

 vertical and narrower, those of adjacent corallites usually continuous over the inter- 

 calicinal partitions, exsert to '5 or 1 mm., septal edges and exsert ends well toothed, sides 



