26 



frnctured base thirteen lines ; the diameter of the cup one inch, and the depth of the cup five 

 lines. Other examples apparently referable to this species exhibit a diameter of from one inch 

 and a quarter to one inch and a half. 



Locality and Formation. Corniferous Limestone of Port Colborne, 



17. HELIOPHYLLUM CAYUGAENSE (Billings). 

 (Plate V. Fig. 2.) 



Hdiopliyllum Cayugaense (Billings), Canadian Journal, new series, Vol. IV. p. 124. 



Corallum simple, turbinate, straight or curved. Septa ninety at a diameter of two 

 inches ; one hundred and eighty at a diameter of three inches and a half. Arched septal 

 stripe and spines thick and strong, separated from one another by intervals of a line or a little 

 less. Calice with a flattened space at the bottom, and a septal fossette on one side. Epitheca 

 with numerous sharp encircling ridges and folds of growth. 



This species is closely related to H. Canadense (Billings), from which it is separated by 

 the possession of a flattened space at the bottom of the cup, and by the somewhat greater 

 remoteness of the septal striae and spines. 



Specimens with a calice of two inches across, seem to have been about five or six inches 

 in length, but individuals of the species appear to have attained a much larger size. 



Locality and Formation. Rare in the Corniferous Limestone of Port Colborne, and 

 other localities in Wainfleet. 



18. HELIOPHYLLUM HALLI (Edwards and Haime). 

 Strombodes heUanfkoides (Phillips) ; Pal. Foss. p. 10. Plate V. Fig. 13. a. 



Plate II. 



Hdiopliyllum Halli (Edwards and Haime) ; Brit. Foss. Corals, p. 235. 

 Fig. 3, and Pol. Foss. des Terr, Paleozoiqaes, p. 408, PI. VII, p. 6. 



Heliophyttum Halli; (Billings) Canadian Journal, New Series, Vol. IV. Fig. 126. 



Corallum simple, broadly turbinate, cylindrical, or cylindro-conic, often variously curved. 



Septa 80 to 85, slightly twisted towards the centre. Septal ridges and spines separated by 



intervals of from half to one-third of a line, or even less. Calice circular, moderately deep, with 



a small septal fossule. Epitheca with encircling annulations of growth, but seldom exhibiting 



septal ridges when perfect, or at most very faintly. 



The form and curvature of this species are extremely variable, and the size no less so ; 

 whilst the intervals between the septal spines and strise vary so much that it seems doubtful 

 if much reliance can be placed on this character in the discrimination of species. The exam- 

 pies of this species from the Corniferous Limestone are mostly of large size, and are not parti- 

 cularly well preserved. Those from the Hamilton group are as a rule small, and occur in a 

 state of exquisite preservation. 



One very marked feature in Heliophyttum Halli, as exhibi- 

 ted in all the Hamilton examples except the smallest, is the 

 mode of growth, which is by a peculiar form of calicular 

 gemmation. When the coral has grown to a certain length, 

 the epitheca gradually extends over the original calice in 

 whole or in part, and a fresh corallite is produced from the 

 primitive oral disc by calicular gemmation, generally from 

 one side of the old cup. After this has lived for a certain 

 period, a third cup is produced in a similar manner ; and 

 so the process may be continued, till an aged specimen may 

 consist of six or eight cups arranged in a vertical series, 

 each springing from some, portion of the calice of its prede- 

 cessor. This mode of growth, also, causes a singular irreg- 

 ularity in the form of corals of this species, old examples 

 often looking like a succession of inverted cones inserted 



Bpeeimeivfrom the Hamilton Formation one i nto tne other, whilst the curvature of the whole becomes 



equally irregular by the bending of the successively producedL 



Fig. 4. 



of Arkona. 



