DEVONIAN ROCKS OF WESTERN CANADA. 43 



of F. Gothlandica, whilst the size of the corallites is on the average 

 much more considerable. In fact, the commonest condition in the 

 specimens here alluded to is that alternating portions of the mass 

 exhibit the complete tabulae characteristic of F. Gothlandica and 

 the incomplete tabulje characteristic of F. hemispherica. Mr. Billiiags 

 has also pointed out that the same corallite sometimes exhibits 

 complete tabulae in one portion of its course and incomplete tabula 

 in another. 



As to the condition of the septa, the diagnosis of the species would, 

 perhaps, be altered for the better by the statement that as a genei'al 

 ru.le the septa are absent, or at any rate are iiideterminable. They 

 are, however, not uncommonly to be recognized in the form of small 

 inequalities or min\ite tubercles on the interior of the walls of the 

 corallites ; and they sometimes exist in the condition of distinct 

 spines, though I have never noticed this state of things in any of the 

 specimens from the Corniferous Limestone. It is, however, not 

 uncommon in Silurian specimens, and it has been observed and 

 figui-ed by Mr. Billings from Canadian examples found in the Corni- 

 ferous formation. 



Adult colonies of F. Gothlandica usually have the foi'm of much 

 depressed pyriform masses, but great variations exist in this respect j 

 and young colonies are usually spheroidal or simply pyriform, whilst 

 the largest and oldest aggregations tend to assume the form of dome- 

 shaped or hemispheric masses. The colony is based upon a concen- 

 trically-wrinkled epitheca, which is very commonly wanting in 

 decorticated specimens, and attains a considerable thickness in aged 

 examples. 



Locality and Formation. — Common throughout the Corniferous 

 Limestone in Canada West. 



II. Favosites basaltica (Groldfuss). 

 It is with regard to this species that I find myself compelled, 

 though with great diffidence, to differ from the conclusions arrived at 

 by Mr. Billings (Canadian Journal, Yol. iv. p. 106), more widely than 

 as concerns any other form described by him. Having, however, had 

 the opportunity of examining a very extensive series of specimens, 

 I cannot at present accept his .views with regard to the limits of this 

 species. It seems pretty certain, to begin with, that the forms 

 included by Goldfuss {Petref. PL xxvi. figs. 4 a — d) ixnder the name 



