46 ON THE SPECIES OF PAVOSITES OF THE 



radiating septa represented, sometimes cleai'ly, sometimes indistinctly, 

 hj a number of longitudinal ridges or striae. 



The typical examples of this species are visually spheroidal, cylindroi- 

 dal, or club-shaped, and possess almost perfectly cylindrical corallites. 

 The corallites are large and small, each larger one being surrounded 

 by an incomplete ring of smaller. The larger corallites are uniformly 

 about a line and a half or a line and three quarters in diameter ; but 

 the smaller corallites vary considerably in size, from an eighth of a 

 line up to almost a line. The mural pores often cannot be made out, 

 but in all the specimens I have seen there are constantly two rows of 

 pores on the larger corallites, thus differing materially from F. basal- 

 tica, Gold. Mr. Billings, however, states that the smaller tubes 

 possess but a single row of mural pores. The condition of the 

 tabulae is exceedingly peculiar ; and I do not think it can be due, as 

 suggested by Mr. Billings, to the manner in which fossilisation was 

 effected ; since it is constantly present in all our Canadian example^ 

 of this species, whilst these occur side by side with examples of 

 F. Gothlandica in which the tabulee are complete. The tabulae, 

 namely, are present in an incomplete and rudimentary form, being 

 represented by numerous close-set lamellae, ridges, or short spines, 

 which project a short way into the interior of the corallite, giving it 

 a most peculiar and easily-recognised appearance. The most perfectly 

 preserved specimen in my possession, in which the tubes are filled 

 up, instead of being as usual hollow, exhibits tabulae which are 

 slightly more developed than those just described, approximating 

 closely to what is observable in F. hemispherica. The tabulae, 

 namely, in this specimen, are close-set, thin, flexuous lamellae, which 

 for the most part extend almost half way across the corallite, often 

 bifurcating or interlocking at their free ends ; but which in some 

 instances acttvally become complete, and pass right across the corallite. 

 The radiating septa are quite rudimentary, and, when discernible at 

 all, have the form of obscurely-marked longitudinal striae. Lastly, 

 I have observed in several specimens, especially in those of a cylin- ■ 

 droidal or clavate form, the peculiar feature that the calicos of a 

 greater or less moiety of the colony are closed by an epitheca, closely 

 resembling what is observed in F. turhinata, Billings. 



Mr. Billings has shown that small specimens having the characters 

 above mentioned pass by a perfect transition into, much larger pyri- 

 form specimens, which present the peculiarity that the corallites at 



