SÜBCLASS III 



ALCYONARTA 



111 



Family 5. Helioporidae Moseley.^ 



Calcareous coraMa, composed of two series of tuhiform corallites ; the larger tubes 

 (autopores) are embedded in a strongly developed coenenchyma made up of smaller 

 tubes (siphonopores). Both autopores and siphonopores are dosely tabulate ; the 

 autopores are provided with ridge-like pseudosepta, which, however, do not correspond 

 numerkally with the tentacles. 



The affinities of the Helioporidae with the Alcyonaria were first pointed out 

 by Moseley. The larger polyps inhabit the autopores, and are furnished with 

 eight mesenterial folds and a crown of eight tentacles ; while the smaller 

 polyps, which are without either tentacles or sexual organs, are lodged in the 

 siphonopores. The skeleton is composed of calcareous trabeculae, the same as 

 in the Hexacoralla, from whose centres of calcification radial fibres extend 

 outwards in caespitose fashion. The siphonopores multiply by intermural 

 gemmation, while the autopores 

 are formed by the coalescence 

 and fusion of a number of the 

 siphonopores. 



Heliopora Blainv. (Fig. 174, 

 A, B). Corallum massive or 

 ramose; autopores with 12-25 

 slightly developed pseudosepta, 

 and embedded in a coenen- 

 chyma made up of smaller 

 siphonopores : the latter are 

 more closely tabulate than 

 the autopores. Cretaceous to 

 Recent. 



Polytremacis d'Orb. (Fig. 174, C). Like Heliopora, but pseudosepta much 

 more strongly developed, sometimes reaching nearly to the centre. Cretaceous. 



Octotremacis Gregory {Polysolenia Reuss non Ehrenb.). Miocene ; Java. 



Fig. 1T4. 



Heliopora partschi (Reuss). Upper Cretaceous ; St. Gilgen on 

 Wolfgangsee, Salzkammergut. J, Corallum, natural size. iJ, Por- 

 tion of surface, enlarged. C, Polytremmis hlainvilleana Reuss. 

 Upper Cretaceous ; Gosau, Salzkammergut. Vertical section, 

 enlarged. 



Family 6. Heliolitidae Lindström.2 



Corallum. massive, more rarely ramose, varying from spheroidal to flabellate, 

 composed of tubulär or vesicular coenenchyma enclosing corallites in the form of large 

 cylindrical and numerous smaller angular cells ; both the macro- and microcorallites 

 with tabulae. Usually twelve septa present in the large cylindrical cells, but these 

 are often rudimentary. No mural pores ; basal epitheca present. Silurian and 

 Devonian. 



The genera assigned to this family exhibit in their general appearance, 

 finer structure and manner of multiplication, considerable resemblance to 

 Heliopora, with which they were associated by Moseley, Nicholson, Bourne, 



1 Moseley, IL N., The Structure and Relations of Heliopora caerulea. Pliilos. Trans. Royal 

 Society, 1877, vol. clxvi. — Bourne, G. C, On the Structure and Affinities of Heliopra caerulea. 

 Ibid., 1895, vol. clxxxvi. pt. 1. 



2 Lindström, G., Reniarks on the Heliolitidae. K. Svensk. Vetensk. Akad. Handl., 1899, 

 vol. xxxii. — Klär, J. , Die Koralleufauna der Etage 5 des norwegischen Silursystems. Palaeontogr. 

 1899, vol. xlvi. — Idem, Revision der mittelsilurischen Heliolitiden, etc. Videnskabs-Selskabets 

 Skrift. I. Classe, No. 10, 1903. 



