82 CONTRIBUTIONS TO CANADIAN PALAEONTOLOGY. 



Lower Helderberg group. — West of 1' Anse a la Bar be, Baie des Chaleurs, 

 W. E. Logan, 1843, (identified by E. Billings), l'Anse a la Vieille, Baie 

 des Chaleurs, R. Bell, 1862, and two specimens from l'Anse a la \£ieille 

 probably collected by J. Richardson. 



Genus Plasmopora, Milne-Edwards and Haime, 1849. 

 (Compt. Rend., t. XXTX, p. 262.) 



Propora, Milne-Edwards and Haime. 1849. Compt. Rend., t. XXIX., p. 262. 



Corallum hemispherical or irregularly massive, with a convex upper 

 surface ; corallites long, cylindrical, at right angles to the surface, distant, 

 their interspaces filled with numerous parallel, polygonal tubules defined 

 by distinct walls ; tabulae of the corallites regular, horizontal, numerous, 

 those of the tubules convex, interfering with the regularity of the walls ; 

 septa twelve in number, well developed, sometimes almost obsolete, con- 

 fined to the corallites. 



The chief point of difference between Heliolites and this genus is, that 

 whereas, in the former the tubules have regular, well-defined, vertical 

 walls and horizontal tabulae, similar to those of the corallites but more 

 numerous, in the latter the tubules are filled with convex plates that dis- 

 turb the orderly arrangement of the walls, causing them to be irregularly 

 zigzag instead of straight in their upward growth. 



Plasmopora follis, Milne-Edwards and Haime. 

 Plate II, figs. 8, 8a. 



Plasmopora follis, Milne-Edwards and Haime. 1851. Polyp. Foss. des Terr. Palaeoz., p. 

 223, pi. 16, figs. 3, 3a. 

 ii ii Rominger. 1876. Geol. Sur. Mich., Foss. Corals, p. 13, pi. Ill, 



fig. 2. 



This species is found in the form of large masses, sometimes 6 inches 

 in breadth, of somewhat irregular shape, generally convex above and pre- 

 sumably covered below by an epitheca. Corallites from 1*25 to 1*5 mm. 

 in diameter, circular, distant from *3 to 1 mm. Tubules polygonal, from 

 one to three in the shortest line between neighbouring corallites. Tabulae 

 are present in the corallites \ they are horizontal, from three to five occur- 

 ring in a space of 1 mm. In longitudinal sections convex tabulae are seen 

 in the tubules, giving the ccenenchymal structure a vesicular appearance; 

 and whereas in transverse sections the polygonal outlines of the tubules 

 are clearly defined, in longitudinal sections the tubular walls appear as 

 zigzag vertical lines, rendered obscure by their amalgamation with the 



