88 



COELENTERATA—ANTHOZOA 



PHYLUM II 



Bhizophyllum Lindst. Corallum simple, pyramidal or hemispherical, 

 flattened on one side ; external surface corrugated, and sending ofF hollow, 

 root-like epithecal processes. Calice marked with septal Striae ; internal 

 structure consisting of vesicular tissue and stereoplasma. Operculum in form 

 of semicircular plate ; inner surface traversed by median ridge and fainter, 

 granulated, parallel elevations. Silurian. 



Calceola Lam. (Fig. 125). Corallum simple, semi-turbinate, or slipper-shaped, 



Fio. 123. 



Strephodes mnrchisoni Lonsd. 

 Showing strongly developed 

 dissepiments and tabulae. 



Fk.. 124. 



Goniophyllum pyramidale 

 (His.). Silurian ; Gotland. 



A , Specimen with operculum. 



B, Calice seen from above. 

 Natural size (after Lind- 

 ström). 



Calceola 

 Devonian ; 



Fig. 125. 



sandalina Lam. 

 Eifel. Natural 



with one side flat and triangulär. Calice very deep, extending nearly to apex, 

 and marked internally with fine septal Striae. Cardinal septum placed in the 

 centre of the vaulted side, counter septum in middle of flattened side, and alar 

 septa at the angles. Internal structure composed of fine vesicular tissue and 

 Stereoplasma. Operculum semicircular, very thick, under surface marked with 

 prominent median and fainter lateral septal ridges. C. sandalina Lam. Very 

 common in Middle Devonian of Europe, rare in Carboniferous Limestone of 

 Belgium. 



Range and Distribution of the Tetracoralla. 



The typical Tetracoralla are confined to the Paleozoic rocks. They are 

 unknown in the Cambrian, and make their first appearance in the Ordovician, 

 where they are sparsely represented in North America and in Europe. Here 

 the most abundant genus is Streptelasma, and next in order of importance are 

 Cyathophyllum, Ftychophyllum and Columnaria. The maximum development 

 falls in the Silurian, which contains the largest number of genera and species. 

 There are limestones found on the Islands of Gotland and Dago (Esthonia), as 

 well as at Dudley, Shropshire, at Lockport, New York and other places in 

 North America, which are made up of ancient coral-reef s. The principal agents 

 concerned in the formation of these reefs were Cyathophyllum, Heliophyllum, 

 Omphyma, Ptychophyllum, Sfromhodes, Acervularia, Stauria, Aulacophyllum, Cysti- 

 phyllum, etc., of the Tetracoralla, besides numerous Tabulata, Octocoralla, 



