KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 



32. n:o i. 89 



rudimentary structure agrees. Sardeson has said^ that »die Zertheilung der Mauern» (to 

 wit in the coenenchyraa) »ist bei Plasraopora-Propora trotz des höheren geologischen Alters 

 bereits weiter fortgeschritten als bei Heliopora». And »bei Propora geht die Reduction der 

 Wände am weitesten». He has thus clearly expressed his opinion that Propora is a genus 

 in the act of regress from a former more complete state. I think the case is qnite the 

 opposite and that these oldest forms of all Heliolitidse are in a state of progress. The 

 aculas, bacilli and baculi which have grown amongst the ever present vesicular tissue are 

 the fundaments, out of which the tubuli in låter times have been developed, as is so well 

 seen in the Plasmopora?, which are, as it were, intermediate between Propora and Heliolites. 

 They are not remnants of already dissol ved tubuli, on the contrary the rudiments out of 

 which the tubuli are built up. 



It is also remarkable that the youngest species of Propora, as P. tubulata, in certain 

 respects come near to the Plasmoporas, especially to Plasmop. scita and show a sort of 

 precursory formation of aureola in its costa?. 



The almost absolute defect of the coenenchyma or its scarcity in some of the 

 specimens belonging to Prop. conferta (see pl. viii, tigs. 32, 34, 37 and pl. ix, figs. 31, 3'2), 

 and also another species (pl. ix, figs. 33, 34), is a feature which leads to the assumption 

 of still older twelve septate corals without any coenenchyma at all, from which the true 

 Heliolitidag may have descended. 



Propora tubulata. Lonsdale. 



Pl. VIII, figs. 4—22, 24, 25, 28—31. 



1838. Astrsea densistellata ÄNQELIN. Museum Palseontologicum Scaiidinavicum, N:o 11. 



1839. Porites tubulata LONSDALE. Sil. Syst., p. 687, pl. 16, tigs. 3, 3a— 3/. 



1850. Propora tubulata E. & H. Brit. Foss. Cor. Introd., p. IL-o. 



1851. » » IlD. Polyp, paléoz., p. 224. 



1851. Palaeopora tubulata M'COY. Brit. Palreoz. Foss., p. 18. 



1851. Lyellia araericana E. & H. Polyp, pal., p. 226, pl. 14, f. 3, 3a. 



1854. Propora tubulata E. & H. Brit. Sil. Cor., p. 255, pl. 59, f. 3, 3a, U. The Hg. 3ä gives no true 



representation of the interiör structure. 

 1858. » » Fe. Schmidt p. p. Archiv, p. 226. 



1860. » » E. & H. Hist. Nat. Cor. III, p. 241. 



1860. Lyellia araericana B. & H. Ibid. III, p. 243. 



1867. Propora tubulata LiNDSTR. Nomina Foss. Gotl., p. 27. 



1867. Heliolites (Propora) tubulatns Salter in MURCH. Sikiria, pl. 39, figs. 3 — 3/. 



1880. Plasmopora girvanensis NiCH. & Eth. Girvan, p. 266, pl. XVII, fig. 2. 



1882. Lyellia aniericaua J. Hall. Il*'' Rept. Indiana, pl. XLVII, f. 5, p. 381. 



1883. Propora tubulata F. ROEMER p. p. Lethtea Geogn. I, p. 512, fig. 122 ohs. The hgure and probably also 



the description are raore consonant with Pr. conferta. 

 1883. Plasmopora tubulata LiNDSTR. in Eichthofbn's China, Bd iv, p. 60. 

 1885. » » Id. List. Fossils Gotl., p. 18. 



1888. » s ID. List. U. Sil. Faunas Sweden II p., p. 21. 



* Tabulaten, p. 282. 



