iambe. ] CANADIAN PALAEOZOIC CORALS. 67 



Temiscaming, at Cross Lake Rapids on the Saskatchewan River and at 

 Cedar Lake, and from rocks of nearly if not the same age in Anticosti, the 

 tubules are from | to ^ the width of the corallites. 



Particular stress has been laid on the presence or absence of septal 

 spines by Dr. Nicholson. In his " Palaeozoic Tabulate corals," p. 229, it is 

 stated that " the form known as H. escharoides, Lam., is distinguished from 

 the typical H. catenularia, Linn., not only by the superficial characters 

 just mentioned,* but also by the constant possession of spiniform septa, 

 and the apparantly constant absence of small tubes between the 

 large ones." This is not borne out, however, by Canadian specimens. 

 An example from the Niagara limestone of Ontario has tubules between the 

 corallites admirably shown as well as rows of septal spines ; other examples 

 with tubules and septal spines have been collected at Lake Temiscaming 

 (Niagara), at Cross Lake Rapids on the Saskatchewan River and at Cedar 

 Lake (Niagara) and from the Lower Helderberg rocks of l'Anse-au-Gascon, 

 TAnse a la Barbe, &c, Baie des Chaleurs. When the tubules are present 

 and the septal spines are not seen, it is possible that the latter, on account 

 of their small size, have not been preserved or are not sufficiently distinct 

 to be recognized. 



The gradation of one form of H. catenularia into another would lead 

 to the belief that it consists of one typical form with several stratigraphical 

 varities ; the typical form not being the oldest. 



It is found however that the Halysites of different geological horizons 

 have distinctive characteristics which are apparently constant. This is 

 important as affording a guide to the determination of the relative ages 

 of the earlier Palaeozoic rocks in this country, and as placing a value on 

 the occurrence of Halysites in these rocks far greater than it has hitherto 

 had. 



Taking //. catenularia, L., as the type of the species and regarding the 

 coral as found in rocks of Niagara age, and distinctive of that formation 

 in Canada, as its equivalent in this country, it is the opinion of the writer 

 that the divergent forms, whilst sufficiently distinct for varietal differenti- 

 ation, would scarcely admit of specific separation : they are here regarded 

 as varieties yet distinctive of definite horizons. 



A table,! for comparative use, has been prepared from data obtained 

 from Canadian specimens, the property of the Geological Survey, giving 

 measurements of the corallites and tubules, the shape and distance apart 

 of the tubulse, and stating whether septal spines have been observed or 

 not, with the name of the collector, date of collection and formation 



* The size of the tubes (corallites) and the dimensions of the meshes of the corallum. 

 t Page 74. 



