Prof. H. A. Nicholson — On the Genus Favosites. 567 



II. — On the Species of Favosites ekom the Devonian Eocks of 

 Western Ontario.^ By Prof. H. Alleyne Nicholson, M.D., 

 D.Sc, etc., etc. 



fPHIS paper is intended by Prof. Nicholson to supplement one by 

 JL Mr. Billings on the Devonian Corals of Canada West (Canadian 

 Journal, new series, vol. iv. p. 97), with some of whose conclusions, 

 as to the species of Favosites, Prof. Nicholson is unable to agree. 



The genus Favosites, Lam., comprises branched or massive corals, 

 comjDOsed of numerous more or less polygonal corallites, divided 

 internally by transverse septa or "tabulee," sometimes quite rudi- 

 mentary. The walls of the corallites are perforated by one, two, 

 three, or more rows of mural pores. The septa are absent or 

 rudimentary, being at most represented by tubercles or short spines. 



PalfBontologists are not agreed as to the generic limits of Favosites, 

 and several new genera have been founded, which Prof. Nicholson 

 gives reasons for rejecting. 



The numerous species of Favosites may be divided into two 

 groups — massive and ramose ; F. GotJilancUca being the type of the 

 former, and F. polymorpha of the latter. 



The following characters have been relied on for separating the 

 species of this genus : — 1. The diameter of the corallites ; 2. The 

 equality or inequality of their size ; 3. The completeness or incom- 

 pleteness of the tabiilge ; 4. The number of rows of mural pores ; 

 5. The position of the mural pores ; 6. The presence or absence of 

 rudimentary septa. 



For convenience of reference, the author gives the following table 

 of the more important species of Favosites, it being remembered 

 tbat some of them are perhaps not valid, and the number of rows of 

 mural pores not constant even in the limits of the same species. 



A. Massive species. 



a. Tabulas complete. One row of mural pores, placed on the 

 faces of the corallites. 



1. Favosites basaltica, Goldf. 



2. Favosites turbinata, Billings. 



h. Tabula complete. Two rows of mural pores, placed on the 

 faces of the corallites. 



3. Favosites Gothlandica, Lam. 



4. Favosites Niagarensis, Hall. 



c. Tabulge complete. Three rows of mural pores, placed on the 



faces of the corallites. 



5. Favosites multipora, Lonsd. 



6. Favosites Troosti, Edw. and Haime. 



d. Tabula complete. Mural pores situated in the angles formed 



by the prismatic walls of the corallites. 



7. Favosites alveolaris, Goldf. 



8. Favosites aspera, Goldf. 



e. Tabulae more or less incomplete. Mural pores in one, or 



more commonly two rows. 



1 From " The Canadian Joui'nal." 



