Primanj S<'j>(al I'iioi of the Ruyosa. ',\')1 



\\'Ii(Mi Kuiitli, ill ]<S()ll*, first clearly demoiistratoil tlic} 

 lomaikahK', pinnate mode of septal development so charac- 

 teristic of the Rugosa, iji which new septa arc added at tour 

 distinct ])oints in the circumlerence of the corallum, he natu- 

 rally inferred, in the absence of direct evidence, that these 

 corals had four primary septa. But whenever actual investi- 

 gation of the point has occurred, not four but six se|)ta have 

 been found. Thus Pourtales, in 1871 f, in the youngest 

 stage ho examined in Lophophijllam proliferam found six 

 septa only, so symmetrically arranged that he regarded them 

 as primary. It was not till 1902 that the matter was again 

 taken up. In that year Duerden published an important 

 paper X ill which Pourtales's conclusions with regard to 

 L. prolifenim were fully supported and in which an inter- 

 esting relationship of the living Zoaiitheai to the Uugosa is 

 suggested ; this paper also contains an excellent survey of 

 the literature of the subject. In a later paper § the same 

 author incidentally figures another instance where he has 

 found six septa symmetrically arranged in the youngest 

 stage examined in Streptelasma rectum^ and which he regards 

 as primary; and while pre[)ariiig tiiis manuscript for jjublica- 

 tion I have seen, through the kindness of Dr. Ashworth, an 

 advance proof of a further note by Duerden ||, in which lie 

 gives a list of five additional species in which six septa, 

 presumably primary, have been observed. 



On the other hand, it may fairly be said that no evidence 

 has yet been brought forward conclusively demonstrating the 

 presence of a primary four-rayed condition in these corals, 

 though quite recently Gordon ^, from examination of an 

 Ordovician Streptelasma, has concluded that in that form 

 there were four primary septa, and that of the six observed 

 by Duerden in the Carboniferous Lophophyllum four were the 

 true primary ones and the remaining two " accelerated 

 secondary septa/'' It is hoped that in the course of the 

 present paper it will be shown that Gordon's careful observa- 

 tions are in no way inconsistent with the presence of a 



* Kuuth, A., " Beit, zor Keuat. foss. Koralleu," Zeit. d. Deut. Geol. 

 Ges. xxi, 



t Pourtales, L. F. de, " Deep-sea Corals," lllus. Cat. Mus. Cotup. Zool. 

 Harvard Coll. iv. 



I Duerdeu, J., '" Relationships of the Eugosa to the living Zoanthese," 

 Ann. & Mag. Nat. Hist. (7) ix. 



^ Duerden, J., " The Fossula in Rugose Corals," Biol. Bull. vol. ix. 

 no. 1 (1905). 



II Duel den, J. E., '• The Priuiai'v Septa in Rugose Corals," ' Science,' 

 Aug. i'4, I'JUO, p. 246. 



H Gordon, C. E., " Early Stages in Paiteozoic Corals," Amer. Journ. 

 Sci. (4) xxi. (I'JOtJ). 



