110 PEKCY SLADEN TRUST EXPEDITION 



spinulose, up to 55 in number, average about 40; of these 12 — 18 meeting columella, 

 usually 15 — 17, each with up to 10 spinulose solid teeth, usually becoming longer towards 

 columella. The subsidiary septa often curving towards and ftising with sides of principals 

 near to columella, up to 3 or 4 on one side of a principal septum. An alternating cycle of 

 very narrow septa present, continuous over inter-calicinal walls as in F. vasta (better seen 

 over the walls than within the corallites) and alternating with exsert ends of the main 

 septa. When the inter-calicinal walls are broad, the continuous exsert ends of both cycles 

 are sometimes connected by an incomplete narrow ridge or appear grooved along the 

 middle of the walls. Columella formed of septal trabeculse, loosely spongy or closely 

 twisted, rising into points, about ^ — ^ width of calyx. Multiplication by marginal 

 fission. 



On level regions and especially towards edges the corallites are more regular in shape, 

 hexa- or pentagonal, calices oval or circular but smaller in size, about 10 mm. in diameter 

 and shallower (4 or 5 mm. in depth). The inter-calicinal walls are thickened to about 

 2 "5 or 3 mm. and appear furrowed; the septa are also thickened, especially towards the 

 walls, with the teeth reduced to 3 or 4 in number but swollen at their bases, the lowest 

 ones becoming upright and simulating a pali-crown ; the columellae are formed of inter- 

 lacing septal teeth. These regions of the corallum vary towards the hirsuta facies, 

 but the corallites are much smaller and the corallum much less massive. Ehrenberg's 

 type of Favia coniplanata, which is an edge-piece, has exactly the same appearance. 



This species is variable to even a greater extent than F. abdita, all the stages from 

 a light corallum with thin walls and septa to a heavy corallum with thick walls and septa 

 being present. It resembles F. abdita in (1) having the same type of hillocky growth, 

 with distorted corallites, (2) fissioii being marginal and very unequal, (3) up to 3 or 4 

 subsidiary septa fusing with one side of a principal septum ; but differs from it in that the 

 septa are further apart and less in number, the corallum more spiny and on the whole 

 having a thicker facies. 



The present species also approaches F. vasta (Klunz.) in that the two cycles of septa 

 are continuous from corallite to corallite over the intervening walls, the consequent 

 alternating appearance of large and small exsert ends being a characteristic feature of 

 both ; but in F. vasta the corallites are larger and the corallum is without the hillocky 

 mode of growth. 



Most of my specimens have the same facies as Ehrenberg's type (19 x 8 x 9 cm.) of 

 Astrcea tesserifera. In the Paris Museum are eleven good examples (the largest 

 30 X 23 cm.) from the Red Sea, refer-red by Milne Edwards and Haime to Prionastrcea 

 tesserifera, showing much of the variation possible in this species. 



Locality. Red Sea (12). Not recorded from any other locality. 



19. Favia HEMPmcHii (Ehrenberg). (PL 27, figs. 1, 2 and 4 ; 36, fig. 3.) 



1834. Astrcea hemprichii, Ehrenberg, Oorall. roth. Meer., p. 96. 



? 1834. Astrcea dipsacea (pars), Ehrenberg, Corall. roth. Meer., p. 97. 



1851. Prionastrea hemprichi, Milne Edwards and Haime, Pol. foss. terr. palseoz., p. 102. 



1857. Prionastrcea hemprichi, Hist. Nat. Corall., ii, p. 521. 



1879. Prionastrcea spinosa, Klunzinger, Korall. Roth. Meer., iii, p. 39, pi. 4, fig. 7 and pi. 10, fig. 5. 



? 1879. Acanthastrcea hirsuta var. microstoma, Klunzinger, Korall. Roth. Meer., iii, p. 42, pi. 5, fig. 2. 



