322 Prof. H. A. Nicholson on some new or 



guished from this by the much finer structure of the skeleton, 

 as also by the exceptional relative thickness and the very 

 regular development of the connecting-processes of the radial 

 pillars. The areolated aspect of tangential sections, resulting 

 from the characters last mentioned, is indeed the essential 

 peculiarity of A. Whiteavesii. Another very characteristic 

 feature, by which the species is distinguished from allied 

 forms, is the reduction of the astrorhizee to their vertical 

 canals only and the arrangement of the apertures of these in 

 more or less definite rosette-like groups. 



Formation and Locality. Devonian, Little Red River, 

 Canada {coll. Geol. Survey Canada). 



Actinostroma matutinum, Nich. 

 (PI. IX. figs. 1 and 2.j 



Ccenosteum massive, the larainge undulated in such a way 

 as to give rise to rounded eminences. Astrorhizse apparently 

 wanting, or at any rate imperfectly developed. 



Vertical sections (PL IX. fig. 2) show strong radial pillars 

 united at short intervals by stout "concentric laminse." 

 About six or seven radial pillars occupy a space of 2 millim. 

 measured transversely, wliile nine to twelve " concentric 

 laminae " occupy the same space measured vertically. Owing 

 to the undulation of the laminae tangential sections (PI. IX. 

 fig. 1) are more or less unsatisfactory, as they necessarily cut 

 obliquely across several successive laminae ; but they show 

 the large rounded ends of the transversely divided pillars, 

 united in places by thick connecting-processes. 



Ohs. Having mislaid my original notes on this type, and 

 having returned to Mr. Whiteaves the specimens upon which 

 these were based, I am not at this moment able to charac- 

 terize the present species otherwise than by its microscopic 

 structure. So far as this is concerned the species seems to 

 be intermediate in character between A. clathratum, Nich., 

 and A. fenestratum^ Nich., its distinctive features being the 

 thick radial pillars and the strong, close-set, and regularly 

 developed " concentric laminae." 



Formation and Locality. Chaleur Group, Div. 1, L'Anse 

 au Gascon, Quebec [coll. Geol, Survey Canada). 



Actinostroma fenestratum^ Nich. 

 (PI. X. figs. 3 and 4.) 



Actinostroma fenestratuin,'^\cko\soxi, Mon. Brit. Strom, p. 146, pi. xvii. 

 figs. 8 and 9 (1889). 



The ccenosteum in this species is massive and not definitely 



