GENERA OF FAVOSITlDyE. 71 



in which the tubes are empty, or in transverse sections (PI. 

 III., fig. 3), but which can be with difficulty separated from 

 the imperfect tabulae. The mural pores are most generally 

 biserial, sometimes triserial, and are remarkable for their close 

 arrangement. In the best - preserved calcareous examples 

 which have come under my notice, they form a double row, 

 running down the centre of each prismatic face (PI. III., fig. 

 3 a), sometimes alternately, sometimes oppositely placed, con- 

 tiguous pores in each row being separated by their own 

 diameter or less. The most remarkable feature about the 

 present species, however, is presented by the tabulcs, which 

 can be admirably studied by means of specimens from the 

 Corniferous Limestone of Wainfleet, Ontario, in which the 

 corallum is in the exceptional condition of not only being 

 calcareous, but of being entirely empty and free from foreign 

 matter, thus quite resembling the skeleton of a recent coral. 

 In such specimens it is not unusual to find that the condition 

 of parts is twofold. In some of the tubes, sometimes in the 

 greater number, the corallites are traversed by horizontal and 

 complete tabulae, about five of which occupy the space of two 

 lines, the state of matters in these corallites thus resembling 

 what we see in F. Gothlandica, Lam. In other tubes, again, 

 there are few or no complete tabulae, but the visceral chamber 

 is crossed by a series of incomplete tabulae, in the form of thin 

 foliaceous, irregularly flexuous laminae (PI. III., fig. 3 <5), which 

 only extend to a certain distance inwards towards the axis of 

 the tube, and are often so closely packed as to cause a regular 

 interlocking of their free ends, or even an actual anastomosis 

 or confluence. When viewed from above, these incomplete 

 tabulae often have a regularly radiate arrangement, and thus 

 simulate septa ; but their true nature is rendered obvious by 

 their broad, leaf-like, or tongue-like form, and by their trans- 

 verse extension as regards the axis of the visceral chamber. 

 While many specimens, as just remarked, show a development 

 of complete tabulae in some tubes and of incomplete ones in 

 others, it should be remarked that in other examples, often of 



