10 CONTRIBUTIONS TO CANADIAN PALAEONTOLOGY. 



last, which are frequently not preserved, leaving the walls of the corallites 

 on the inside quite smooth. 



The squamulse occur one above another in longitudinal rows corre- 

 sponding in a general way with the rows of pores, those of one row fre- 

 quently interlocking with those of another. When the mural pores are 

 numerous the squamulse are generally placed one above each pore, but, 

 when fewer in number and farther apart, two or three squamulse are 

 found occupying the space between any two pores of a longitudinal row. 

 From this it would appear that the squamulre may be equally numerous 

 when the pores are distant from each other or when they are placed close 

 together. Most frequently the squamulse have their bases only preserved 

 but under favourable circumstances they are seen to reach the centre of 

 the corallite in the form of thin tongue-shaped processes that are longer 

 than broad and at times inclined slightly upward. 



In different coralla the pores vary in diameter from about 33 to -50 

 mm., and in their distance fi om each other ; in some specimens, especially 

 in those in which the pores are large, they are about '50 mm. from each 

 other, whilst in others they are as much as 2 mm, apart vertically. In 

 most cases the absence of the raised border of the pores is probably due 

 to weathering, as examples occur in which the rim is present in certain 

 portions of the corallum and absent in more exposed parts ; in the case 

 of the latter the pores appear larger than they really are. 



As in some other species of the genus, small marginal depressions in the 

 tabula are not unfrequently developed. 



Broadly expanded examples sometimes measure nearly 9 inches across 

 with a height of 3 or 4 inches; clavate specimens occur that are 10 or 

 more inches high and a few inches thick ; some of the pyriform speci- 

 mens are 6 or 7 inches high and 5 or 6 inches in breadth. 



The large collection of specimens of this species in the museum of the 

 Geological Survey has enabled the writer to study the many transitional 

 stages between examples with large close set pores, which are undoubtedly 

 the F. tuberosa of Rominger, and others that agree in every particular 

 with F. epidermata, Rominger. 



Abundant in the Corniferous formation of Ontario. 



