18 



CHAPTER II. 



CORALS OP THE COENIFEROUS AND HAMILTON FORMATIONS. 



Of all the organic remains of the Devonian Rocks of Canada, and especially of the 

 Corniferous Limestone, none are more conspicuous than the J2prals, whether we take into 

 consideration the vast number of individuals or the great variety of type which they exhibit. 

 Many parts of the Corniferous Limestone are almost wholly made up of corals ; and as these 

 are usually silicified, they weather out of the limestone in a most beautiful manner, and can 

 ie obtained in a state of exquisite preservation. The soft shales of the Hamilton group, also, 

 e often charged with the remains of corals, which, from the decomposition of the surr >und- 

 * matrix, can be obtained perfectly clear of adhering sediment. Mr. Billings in his adtuir- 

 S memoir upon the fossil corals of the Devonian Rocks of Canada West (Canadian Journal, 

 ~? Series, Vol. V., p. 251), estimates the number of corals in the Corniferous and Hamilton 

 Hions as probably about eighty, and of these he describes no less than fifty-four. Some 

 l most striking of these forms, such as the species of Phillipsastrcea, have not come under 

 'ice in any portion of the Corniferous Limestone or Hamilton Group studied by me ; 

 Jvall here describe over seventy species which have come under my personal observation, 

 tht thirty-one belong to the Tabulata, five are referable to the Tubulosa, and thirty -five 

 belong ^ e g rea t g rou p O f the Rugosa. The genera represented are twenty-one in number, 

 viz. : Fugft^ Alveolites, Michelinia, Syringopora, Fistutipora, Chcdetes, Callopora, Striatopora, 

 J.rachypo'1 Aulopora, Zaphrentis, Microcyclus, Blothrophyllum, Clisiophyllum, Heliophyllum, 

 JJipkyphyl^ Eridophyllum, Amplexus, Cystiphylluip, Haimeophyllum and Petnda. Of the 

 species abov twelve can certainly be identified with known European species, viz. : Favosites 

 Crot/ilandica,^ hemisp^rica, F. Forbesi, F. polymorpha, F. ditbia, F. cervicornis, F. reticulata, 

 Aulopora tube orm i s ^ Diphyphyllum gracile, Heliophyllum Halli, Cystiphyllum vesiculosum and 

 MKliel'ima con^^ Besides these well known forms, there are others which are very closely 

 illied to Europt n species, and some which may perhaps turn out, upon fuller investigation, 

 be nothing mce than varieties. 



Genus BLOTHROPHYLLUM (Billings). 



Crew. Char. "lorallum simple, turbinate or cylindrical. Internal structure consisting 



1 a, central area occupied by flat transverse diaphragms, an intermediate area with strong 



ang septa, and an outer area in which there is a set of imperfect diaphragms projecting 



upwards, and bearing on their upper surfaces rudimentary radiating septa. A thin complete 



epitheca, aad a septal fossette " (Billings). 



.. , 7 S6i *t' ra l space of tie theca in corals of this genus is occupied, as in Amplexus, by flat or 

 lexuojstabulse, upon which the septa do not encroach. Outside this central area isanar- 

 :ow zone in whV,h the tabulae are bent downwards towards the base of the coralluin, and are 

 same time \ometimes split and bifurcated, whilst the continuity of the spaces between 

 tnem s interfered w ith by a series of strong septa. Outside this again is an outer zone, 

 rmed by a series oiw^ulae, which are directed upwards and outwards in an arching manner, 

 which carry on tht; r U pp er surfaces a series of imperfect septa, their lower surface being 

 simply costate or ridged. Lastly, the arched tabula? of this external zone are covered by a 

 thin but strong epitheca witv w hich the outer surface of the coral is invested. The genus dif- 

 rrom Zaphrentis in not havi^o- the septa prolonged inwards to, or near to, the centre, and 

 in having the central tabulate area surrounded by a partially vesicular zone and an exterior 

 zone composed of arched tabulae and imperfect septa. From Amplexus it is distinguished by 

 the possession of the external area last mentioned, and by the septa being more largely de- 

 veloped ; whilst it is distinguished from ClisiopliyUum by the first of the above-mentioned 

 peculiarities, and also by the fact that the tabulae of the central area are flat or slightly flexu- 

 ous, and are not elevated into a conical protuberance. 



^ The genus Blothrophyllum was originally defined by Mr. Billings (Can. Jour., New 

 series, vol. iv., p. 129) and the single species B. decorticatum was described. In addition to 

 this previously recorded and very characteristic species, I have now to describe another allied 

 torm, . approximatum, also from the Corniferous Limestone of Western Ontario. 



