100 



ANTHOZOA 



number. Columella sometimes found in the corallites. Bala to 

 Devonian. Ex. H. porosus, Devonian. 



In general structure Heliopora is similar to Heliolites, but is 

 more branching, whilst Heliolites forms rounded or encrusting 

 masses ; further, the smaller tubes which form the ccenenchyma 

 branch dichotomously in Heliolites, but in Heliopora new tubes are 

 introduced between the older ones. By many writers these two 

 genera are considered to be closely allied, but the relationship is 

 denied by others, who state that important differences are found in 

 the structure of the corallite walls and septa. According to Lind- 

 strom and others, the corallites of Heliolites possess a distinct and 





v-< 



■fvf>- a 



V'"" - 









■-• A 



QiTY 





B 



Fig. 40. Heliolites porosus, Devonian. A. Horizontal section. B. Ver- 

 tical section, a, corallites ; b, tubes forming the ccenenchyma ; 

 c, tabular, x 5. 



independent wall (theca) and also have true septa, whilst in Heliopora 

 the corallites are simply bounded by the walls of the coenenchymal 

 tubes, and possess pseudosepta instead of septa and these have the 

 form of ridges except at the openings of the corallites. Bourne, on 

 the other hand, considers that the corallites of Heliolites possess 

 no independent wall, and agree in this respect with Heliopora. 

 Although the ccenenchyma of Heliolites resembles closely that of 

 Heliopora, yet Lindstrom and Kiar maintain that it has originated 

 independently in the two genera, and cannot be taken as evidence of 

 relationship ; this view is based on a study of the development and 



