190 



FOSSIL ACTINOZOA. 



ranging from the Cretaceous to the present day, is another 

 close ally of Turbinolia, from which it differs principally in 

 the possession of a crown of "pali" (fig. 71); while the 

 widely distributed Trochocyathus of the Jurassic, Cretaceous, 

 and Tertiary formations, possesses more than one circle of 

 these structures. 



2. Pseudoturbinolidce. In this family we have only the 

 extinct genus Dasmia, of the Cretaceous and Tertiary, in 

 which the corallum is in most respects similar to that of 

 the Turlinolidce proper, but each septum is composed of 

 three laminae united externally by a single costa. 



3. Oculinidce. The corallum in this family is always 



Fig. 76. Syrihelia Sharpeana. Cretaceous. 



compound (fig. 76), with an abundant and compact ccenen- 

 chyma, its surface smooth or striated, but never echinulate. 

 The wall of the corallites is imperforate, not distinct from 

 the coenenchyma, the lower portion of the visceral chamber 

 becoming filled up with advancing age. A few dissepiments 

 are present, but no synapticulse. 



The Oculinidce appear for the first time in the Oolitic 

 rocks (Huhelia, EnalloJielia), and are also represented in the 

 Cretaceous (Synhelia, fig. 76, and Diblasus). In the Eocene 

 Tertiary we meet with Oculina itself, with its arborescent 

 corallum and nearly smooth ccenenchyma. The well-known 

 living genera Lophohelia' and Amphihelia are found in the 



