imperfectly-known Species of Stromaioporoids. 11 



Clathrodictyon celliilosum, Nich. & Mur. 

 (PI. 11. figs. 7 and 8.) 



Clathrodictyon cellulosum, Nicholson & Murie, Journ. Linn. Soc, Zool. 

 vol. xiv. p. 221, pi. ii. figs. 9 & 10 (1878). 



Coenosteum massive, or in the form of thick laminae. 

 Under surface not observed. Upper surface covered with 

 pointed tubercles, representing the upper ends of the radial 

 pillars, often connected with one another to form sinuous 

 irregular ridges. 



In internal structure the skeleton is composed of remote, 

 horizontal or slightly flexuous concentric laminge. On an 

 average two interlaminar spaces, and therefore three lamina3, 

 occupy the space of 1 millim. The laminee are minutely 

 crumpled or inflected, so as to give rise to oval interlaminar 

 cells which vary in length from about half a millim. up to 2 

 millim. or more. The radial pillars look as if formed by the 

 inflections of the laminse ; but the interlaminar cells are often 

 crossed by delicate partitions ("interlaminar septa"), which are 

 independent of the proper radial pillars (PI. II. fig. 7). The 

 skeleton-fibre is thick and has the aspect^ in vertical sections, of 

 being penetrated by fine vertical tubuli. Tangential sections 

 (PL II. fig. 8) exhibit the remote, oval or round, cut ends of 

 the radial pillars, mostly connected by sinuous lines represent- 

 ing the divided edges of the concentric laminse. AstrorhizEe 

 are apparently not developed. 



Ohs. This species is at once distinguished from all the other 

 forms of Clathrodictyon by the coarseness of the skeletal frame- 

 work. The entire skeleton, in fact, appears in vertical 

 sections to be made up of rows of large oval vesicles. Tan- 

 gential sections are also highly characteristic. 



Formation and Locality. Not uncommon in the Corniferous 

 Limestone (Devonian) of Port Colborne and other localities 

 in Western Canada. 



Clathrodictyon ostiolatum^ Nich. 

 (PI. III. figs. 1-3.) 



Stromatopora ostiolata, Nicholson, Ann. & Mag. Nat. Hist. ser. 4, vol. 

 xii. p. 90, pi. iv. figs. 1, Irt (1873) ; Rep. on the Palaeontology of 

 Ontario, p. 63 (1875). 



Coenosteum massive, composed of concentrically laminated 

 parallel cylinders, which are more or less enveloped by laminse 

 concentric with the entire colony, and which terminate super- 

 ficially in blunt nipple-shaped prominences. Under surface 

 unknown. Surfaces of the laminae smooth or with exceed- 



