58 Pro/. J. W. Gregory — Fossil Corah from Egypt, etc, 



that the Indian coral has more rounded corallites, which are often 

 separated b^' a well-marked furrow ; the furrow is sometimes absent, 

 and then the corallites become polygonal. The columella of S. vicaryi 

 is also rounded. 



PRIONASTRiEA, Edwards & Haime, 1848. 



Prionastr^a lyonsi, n.sp. (PI. YII, Fig. 10.) 



Diagnosis. — Corallum heavy, massive, with apparently subplane 

 upper surface. 



Calices apparently shallow. 



Corallites large, average diameter of 16 mm. ; polygonal and very 

 crowded. 



Septa coarse. An incomplete fourth cycle. Usually the primary 

 and secondary cycles are united to the columella. 



Columella large, but loosely trabecular, and not very well 

 developed. 



Walls inside the corallum are thin and inconspicuous. 



Dimensions. — Covalhiin (fragment of a large corallum) : — 



H 1814 A. II 1812. 



Leno-th 110mm. ... 120mm. 



Wkitli oO ,, ... 85 ,, 



Thickness 75 ,, ... 130 ,, 



Corallites : 



Diameter 16-17 „ 



Calicinal centre : 



Distance lG-1" ,, 



Distribution. — Miocene : plateau, 1,200 feet above the sea, between 

 Camps No. 27 and 28; Wadi Belih, H ISlia; plateau of Abu 

 Sha'ar, H 1812. 



Figuree. — PI. Vll, Fig. lOrt, part of worn surface of the corallum 

 (of H 1814a) showing the rudimentary open columella, nat. size; 

 Fig. Wh. part of thin section of the same specimen, nat. size. 



Affinities. — The two nearest allies of this species appear to be 

 P. irregularis (Defr.),^ from the Miocene of Dax and Turin, which 

 has the same general characters and very thin walls. But that 

 species diti't-rs in that its corallites are only 10 mm. in diameter, 

 and its septa are described by Milne Edwards & Haime as very thin. 

 The nearest ally of P. lyonsi among living corals is P. atistraliensts 

 (Ed. & H.),- which has corallites only 10 mm. diam. P. tesseri/era 

 (Elirb.) ^ is the nearest of the living Eed Sea species, and has 

 corallites of the same size; but it has much thinner septa, and 

 larger, more compact columella. 



' Astrea irregularis, Defrance: Diet. Sci. nat., vol. xlii (1826), p. 381. Frioii' 

 astrrca irrcqidaris, Edwards &^ Haime, 1850 ; aud 1857, Hist. nat. Cor., vol. ii, 

 p. 522. 



2 Edwards & Haime, 1857: op. cit., p. 520. 



* Aatrea tesserlfera, Ehrenberg, 1834, Beitr. Coralleuth. : Abh. k. Akad. "Wiss. 

 Berlin fiii- 1832, p. 321. See Klunziuger, 1879, pt. iii, p. 37, pi. iv, fig. 9. 



{To be coticluded in our next JSrumbei'.) 



