164 CONTRIBUTIONS TO CANADIAN PALAEONTOLOGY. 



" The figure on p. 1 1 3 of the above quoted work represents about one- 

 fourth of the surface of the only specimen of this species in the collection. 

 The specimen is silicified and not preserved as well as might be desired, 

 but by a careful examination of natural longitudinal and transverse sec- 

 tions, the structure can be made out with sufficient clearness to give the 

 following data : — Corallum astrseiform, made up of polygonal corallites, 

 from 3 to 7 mm. in diameter, with deep cidyces that join each other in 

 sharp-edged outlines and that have steep sloping sides and a rounded 

 boss, roughly 2 mm. in breadth at the bottom. Each corallite is contained 

 within its own walls from which spring lamellar vertical septa, whose 

 free edges are moderately conspicuous in the calyces. Septa, numbering 

 from about thirty to forty, alternately long and short, the former con- 

 tinued to the centre, where they are twisted, the latter about one-half, 

 or slightly more than one-half, the length of the former. Dissepiments 

 convex, arching evenly upward and outward, and filling the interseptal 

 loculi in a circumferential area whose breadth is equal to the length of 

 the secondary septa, or about one-fourth the diameter of the corallite. 

 Within the outer area is a zone of dissepiments or vesicles that rise up- 

 ward toward the centre and, in combination with the proximal ends of 

 the primary septa, form a sub vesicular mass that appears at the bottom 

 of the calyx as a rounded projection. 



" The presence of continuous vertical septa, such as the above, in cor- 

 allites that are enclosed by definite walls, makes clear the necessity of 

 removing the species represented by this specimen from the genus Ar- 

 achnophyllum (Strombodes) ; although some details of structure are ob- 

 scured by crystallization, yet sufficient characters are preserved to sug- 

 gest affinities to Acervularia to which genus this species is for the present 

 assigned." (Lambe, 1899.) 



Locality. — Manitouaning, Grand Manitoulin Island, Lake Huron, col- 

 lected by A. Murray, 1847. Niagara group. 



Acervularia Davidsoni, Milne-Edwards and Haime. 

 Plate XIV., fig. 3. 



Acervularia Davidsoni, Milne-Edwards and Haime. 1851. Polyp. Foss. dea Terr. 



Palaeoz., p. 418, pi. IX., figs. 4, 4a, 46. 

 Acervularia Davidsoni?, Hall. 1858. Rep. Geol. Surv. of Iowa, vol. I., pt. II., p. 476, 



pi. I., figs 8a. 86. 

 Acervularia Davidsoni, Nicholson. 1875. Geol. Surv. of Ohio, vol. II., pt. II., p. 240. 



Original description. — " Polypier astr^iforme, a surface subplane, som- 

 mets des polypi^rites en polygenes un peu in^gaux et un peu irr^guliers, 

 dont les c6tes sont un peu en zigzag. Murailles int^rieures peu distinctes au 



