102 G. LINDSTEÖM, HELIOLITIDiE. 



Diploepora. Quenstedt. 



1851. Heliolites p. p. E. & H. Pol. terr. pal., p. 217. 



1881. Diploepora QUENSTEDT. Petrefaktenkunde Deutschl., p. 148. 



This genus is most remarkable through having two widely different sorts of coenen- 

 chyma (pl. xi, f. 4), an older and interiör one entirely of proporidean, vesicular character, 

 and a younger and exteriör of a peculiar nature, rather coccoseridean, coinposed of closely 

 packed, parallel rods or baculi, being of the characteristic featherlike structure. It was 

 ia consequence of this double nature of the coenenchyma that Quenstedt gave it the apt 

 uauie, derived from the greek /ImÅrh] = duplication. As to other particulars, they shall 

 be described in detail further down. 



Diploepora Grayi. E. & H. 



Pl. X, figs. 31—38, pl. XI, figs. 1—4. 



? 1837. Blumeiibacliiura globosum LONSDALE. Sil. Syst., pl. 15, f. 26; acoording to E. & H., Pal. Foss, p. 



217, only a oast of this species. 

 1851. Heliolites Grayi E. & H. Polyp. tevr. pol., p. 217. 

 1855. ■■> IlD. Brit. Foss. Corals, p. 252, pl. 58, f. 1, la. 



1860. » . IlD. H. Nat. Cor. III, p. 238. 



1867. » » LiNDSTR. Nomina foss. Gotl., p. 27. 



1878 — 80. » » NiCHOLSON & EtHBRIDGE. Girvan, p. 58, 252, pl. IV, f. 4, 4a, pl. V, f. 1. It is 



unoertain whether all their specimens really beloiig to this speoies. 

 1879. Diploepora Grayi QUBNSTEDT. Petref.-Kunde Deutsohlaiids, Abtheil. I, Bd 6, p. 147, pl. 149, figs. 2, 3, 4. 

 1883. Heliolites Grayi Ferd. Eoemer. Lethaea Geogn., p. 508. 

 1885. » » Ldm. List of Gotl. Foss, p. 18. 



1888. » i ID. Foss. Faunas of Sweden II, p. 21. 



This species is distinguished from all others in the family through its mode of 

 growth. It is dendroid, branching in terete, fingerlike ramifications or irregular trunks. 

 The English variety is characterised by flat, compressed branches with the dimensions of 

 45 X 5 millim. taken from one specimen. There are fragments of Gotlandic specimens 

 from Ryssnäs in Fårö, measuring 22 decim. in length and 35 centim. across the branches 

 in thickness, proving that it has been one of the largest corals in the Silurian sea. 



It is on all sides covered with tiny, closely set calicles, attaining a diameter varying 

 between O, .5 — 0,8 millims. As may be seen by pl. x, figs. 32 — 35 they have a different 

 shape according to their state of development, fig. 32 representing the youngest, just be- 

 ginning stage, fig. 35 the mature or fully developed one. It is interesting to study these 

 as they elucidate the procedure of the formation of the theca and the septa more evidently 

 than in any other Heliolitidean and consequently are of value for interpreting the origin 

 of the said structures also in other species. 



