170 CONTRIBUTIONS TO CANADIAN PALEONTOLOGY. 



Type species. — P. Bouchardi, Milne-Edwards and Haime. 



Range. — Devonian. 



The chief point of difference between this genus and Phillipsastrcea is 

 that in the latter the distal ends of the septa of individual corallites con- 

 nect with those of adjacent corallites, whilst in the former the union of 

 the corallites is effected wholly or for the most part by peripheral vesicu- 

 lar tissue without the aid of the septa. 



Pachyphyllum is regarded by some well known authorities as a good 

 genus but it is also ranked as a subgenus of Phillipsastrcea, and again the 

 separation of the two genera has been looked upon with entire disfavour as 

 being artificial and inappropriate. 



Pachyphyllum Devoniense, Milne-Edwards and Haime. 



Plate XIV, figs. 8, 8a. 



Pachyphyllum Devoniense, Milne-Edwards and Haime. 1851. Polyp. Foss. des Terr. 

 Palaeoz., p. 397. 

 " " Milne-Edwards and Haime. 1853. Brit. Foss. Corals, p. 234. 



pi. LIL, figs. 5, 5a. 

 Phillipsastrea {Pachyphyllum) Dcvoniensis, Freeh. 1885. Korallen-fauna des Oberdevons 



in Deutschland, p. 67, taf. VI., figs. 2, 2a. 

 Pachyphyllum Devoniense, Whiteaves. 1891. Contr. to Can. Palseon., vol. I., pt. III., 

 p. 205. 



The single specimen referred to this species was collected by Professor 

 Macoun in 1875, on the Peace River, between the mouth of Red River 

 and Vermilion Falls. 



The specimen in question is slightly worn and the finer surface mark- 

 ings consequently lost, but transverse and longitudinal sections have 

 been made that show the structural details of the interior excellently ; it 

 may be described as follows : — Corallum compound, irregular in shape, 

 somewhat subhemispherical, roughly convex above and flat below, 10 cent, 

 in greatest breadth and about 6 cent, high, made up of confluent cor- 

 allites that diverge from a central basal point of attachment. Corallites 

 from about 8 to 1 2 mm. broad, with no demarcation of their outer boun- 

 daries, their centres at the surface projecting 4 or 5 mm. above the sur- 

 rounding margins and forming strongly exsert rings enclosing sunken 

 pits averaging 7 mm. in diameter. In transverse and longitudinal sec- 

 tions the corallites are seen to be made up of an axial area of irregular 

 tabulse surrounded by a cycle of septa that is in turn enclosed within a 

 peripheral zone of vesicular tissue confluent with the like tissue of adja- 

 cent corallites. Septa thick, with smooth sides, numbering from about 

 thirty-six to forty-two, of two orders, primaries and secondaries, the for- 



