NOTES ON THE FOSSILS OF ONTARIO. 



137 



sontal outgrowths of the calice. which are placed at the same level in 

 -contiguous corallifces and form a series of complete floors. Walls of 

 the theca complete anl well developed, meeting in the centre of the 

 theca Avith a distinct and well developed columella. Costal radii 

 prolonged over the successive exothecal floors. Tabulae rudimentary 

 or absent (1). 



-Fio. 4. — AstrcRophijllum graclle, Nich. and Hinde ; a, Side view of a fragment, 

 enlarged, shewing the mural expansions ; b, Fragment Aaewed from 

 above and greatly enlarged, showing the calices, the confluent mural 

 expansions, and the costal radii. 



There are some points in the structure of the corals here referred 

 to which we cannot actually make out with the materials at present 

 in our hands ; and we are therefore uncertain whether they really 

 constitute a new genus, though we cannot place them under any 

 genus already described. 



From Smithia, Edw. and H., the genw^ Astrceophyllum is distin- 

 guished by the possession of a distinct columella, and by the fact that 

 the corallites are united not only by costal radii, but by well develoi^ed 

 exothecal floors. 



From Phillipsastroia, the i^resent genus is distinguished by not 

 having the corallites united laterally along their whole length, and 

 in having the calices definitely circumscribed. 



From ITcdmeophyllum, Billings, the genus is separated by the well 

 developed, not rudimentary, septa, and by the fact that the latter 

 possesses vesicular tabulae. 



From Heliophyllum colligatum, Billings, which probably forms the 

 type of a separate group, Astrceophyllum is distinguished by the 

 possession of a distinct columella, and the apparent absence of septal 

 spines or tabulae. 



From Thecostegites, Edw. and H., the genus is distinguished by its 

 well developed septa und columella, and the apparently obsolete 

 5 



