DEVONIAN ROCKS OF WESTERN CANADA. 41 



I. Favosites Gothlandica (Lamarck). 



The following is the diagnosis given by Mr. Billings of this cosmo- 

 politan species in the paper already referred to : — " Corallum forming 

 spheroidal, pyriform, or large hemispheric or flattened masses ; coral- 

 lites is general between one line and one and a half lines wide, some- 

 times less or more, often two lines ; transverse diaphragms usually 

 complete, i^xrely incomplete ; mural poi-es in one, two or three sei-ies, 

 usually two, those of the same series about half a line distant, some- 

 times less ; pores surrounded by an elevated margin ; faces of the 

 tubes with one or two longitudinal stride, more or less distinctly 

 developed ; radiating sejDta represented by a seiies of small spines, 

 often in the rudimentary form of tubercles." 



The chief characters which may be relied upon as distinguishing 

 typical examples of Favosites Gothlandica, Lam., are the following : 



1. Tlie corallites are of comparatively large size, usually almost one 

 and a half lines in diameter, but varying from one to two lines. 



2. The corallites are generally markedly polygonal, and are for the 

 most part tolerably uniform in their dimensions. 3. The mural pores 

 are in two rows, placed alternately, or sometimes oppositely, on 

 the faces of the corallites, and surrounded by elevated margins. 

 4. The tabulae are complete, that is, extend from one side of the 

 theca to the other. 5. Perfect examples are usually of a more or 

 less hemispheric or pyriform shape, and have their lower surface 

 enveloped in a thicker or thinner, concentrically-wrinkled epitheca. 



Whilst the above characters are generally found to exist in typical 

 specimens of F. Gothlandica, there are, nevertheless, numerous depar- 

 tures from this state of things, which must be attended to in studying 

 this protean species : 



The size of the corallites in some specimens not otherwise separable 

 from F. Gothlandica, is sometimes uniformly below the average in an 

 entire colony, not exceeding one line, or even a little less than this. 

 This might not seem an important difierence, but, as noticed by 

 Mr. Billings, it gives the coral an apparently very distinct general 

 appearance. 



The corallites, though usually distinctly polygonal, are sometimes 

 nearly round throughout an entu-e colony j and their relative size in 

 the same mass may vary to some extent. Thus, it is not uncommon 

 to meet with colonies, in which the great majority of the corallites 



