RUGOSA. 



217 





which it is made up, is often disposed in funnel-shaped 

 layers. In most of the species the calice is open, but in one 

 form (C. prismatic urn) the calice is closed by a lid or oper- 

 cultim, consisting of four 

 or more valves. In the 

 genus Gfoiiiophyllum, of the 

 Upper Silurian, a lid of 

 four valves was present, 

 and the extraordinary De- 

 vonian genus Calceola (fig. 

 113), long referred to 

 the Bracliiopoda, has been 

 shown to be a coral of 

 this family in which the 

 calice is closed by an oper- 

 culum consisting of a single 

 piece. In this connection, 

 it is worthy of notice that 

 some of the living Alcy- 

 onarian Corals (species of 

 Primnoa, Paramuricea, and 

 others) exhibit also a more 

 or less complete operculurn. 

 The calices of Cryptohelia 

 pudica (one of the Hydroid 

 group of the Stylasteridce) 

 are also protected by a cal- 

 careous lamina in front of 

 each. 



Before leaving the Cys- 

 tiphyllidce, a few words 

 may be said as to the 

 singular and problematical 

 fossils termed Beatricea, 

 which, so far, are only 

 known as occurring in 



the Lower Silurian of North America. In these extra- 

 ordinary forms (fig. 114) we have bodies of great size, 



Fig. Il2.Cystiphyllum vesiculosum, showing a 

 succession of cups produced by budding from 

 the original coral. One side of the calice is 

 broken away, and shows the internal structure. 

 Of the natural size. Devonian, America and 

 Europe. (Original.) 



