RUGOSA. 



211 



B 



representative of the Rugosa at present known from deposits 

 of Secondary age, occurring, as it does, in the Lower Green- 

 sand (Cretaceous). The re- 

 maining members of the 

 Stauridce possess a simple 

 corallum. In Metriophyl- 

 lum, of the Devonian, the 

 septa are arranged in four 

 groups, separated by as 

 many fossulse ; and in the 

 Permian Polyccelia the sep- 

 ta are divided by four prin- 

 cipal ones into as many sys- 

 tems. The Tertiary genus 

 Conosmilia may perhaps be 

 associated with the above, 

 but its systematic position 

 is not free from doubt. 



2. Cyathaxonidce. In 

 this family the corallum is 

 simple, the septe are well 

 developed^ and the inter- 

 septal loculi are open, and 

 are not partitioned off by 

 dissepiments or tabulae. In 



many respects this family is very nearly allied to the family 

 of the Turbinolidce, among the Zoantharia sclerodermata, but 

 the septa have a tetrameral arrangement. Cyathaxonia, 

 the type -genus, has a styliform columella (fig. 103), and 

 ranges from the Silurian to the Carboniferous. 1 The living 

 genera, Haplophyllia and Gkiynia, are referred here, but no 

 Secondary or Tertiary members of the family are known. 



3. CyatJwpliyllidce. In this, by far the largest and most 

 important family of the Rugose Corals, the corallum may be 

 simple or compound, the septa are not arranged in a con- 



1 Recent researches have shown that some of the forms usually referred to 

 Cyathaxonia (such as C. Dalmani) really possess tabulae, and are in other 

 respects entitled to be regarded as forming a separate genus, for which the 

 name of Lindstromia has been proposed. 



Fig. 102. A, Small mass of Holocystis elegans, 

 of the natural size ; B, A few caliees of the 

 same, enlarged. Cretaceous. (After Milne- 

 Edwards and Haime.) 



