104 



4. Specimens which are casts of the interior of the frond, to which the innermost mem- 

 brane with the ends of the perpendicular columns still remain attached, are not uncommon 

 (Fig. 40 A & C). These show that the columns are arranged in beautifully regular diagonal 

 lines ; and their inner ends seem to have been convex, as they leave in many cases concave or 

 cupped scars, of an oval or rhomboidal shape, upon the outside of the cast (Fig. 40 B}. 



5. One specimen exhibits a strong horizontal foot-stalk, from which the frond grew up 

 vertically (Fig. 40 C). This foot-stalk is branched at both ends, its surface is covered in 

 pari s with vermicular striae, and its structure appears to have been minutely tubular or cellular. 



6. Lastly, some specimens appear to show the extraordinary character of a second frond, 

 quite similar in structure to the first, invaginated within the outer one, so as to give rise to an 

 internal cone closely applied to the internal surface of the external funnel. It is possible, 

 however, that this appearance may admit of some other interpretation. 



I have treated this species at some length on account of its very remarkable and compli- 

 cated structure ; but there are still several points connected with it which I have been unable 

 to make out with my present materials. Specimens are by no means particularly rare, but I 

 have seen none which are not fragmentary. 



Locality and Formation. Corniferous Limestone of Port Golborne and Lot 6, Con. 1, 

 Wainfleet. 



Genus FENESTELLA (Lonsdale). 



Polyzoary forming a calcareous, flattened or infundibuliform expansion, composed of sub- 

 parallel branches, which radiate from the base, and are united laterally by cross-bars or disse- 

 piments, so as to form a network, the meshes of which are in general more or less oblong or 

 sub-quadrate. One surface of the branches (in the infundibuliform species the inner surface) 

 is rounded and covered by a dense, striated or minutely porous layer. The opposite surface 

 of the branches (in the infundibuliform species the outer surface) is furnished with two rows of 

 short tubular cells, the mouths of which are separated by a more or less prominent carina or 

 keel. The dissepiments are usually without cells. Occasionally a row of small cells upon 

 the mesial keel (the Fenestrellina of D'Orbigny). 



Fenestella differs from Retepora in possessing distinct dissepiments, and in not having 

 the fenestrules formed simply by the coalescence of the branches ; whilst the cells are separated 

 by a distinct keel. From Polypom (McCoy), Fenestella is separated by having only two 

 principal rows of cells, and usually only these two, the third row if present being very minute, 

 whilst the lines of cells are separated by a carina. 



The following species of Fenestella occur in the Corniferous Limestone and the Hamilton 

 group of Western Ontario ; though there are others which cannot be determined until more 

 complete materials shall have been collected. 



127. FENESTELLA MAGNIFICA (Nicholson). 



Polyzoary forming a flattened expansion of unknown but apparently considerable size. 

 Branches almost perfectly straight, bifurcating at intervals of from one quarter of an inch to 



one inch, nearly parallel, united by straight transverse 

 dissepiments, sub-angular or obtusely carinated and closely 

 striated on the non-cell uliferous side. About four branches 

 in the space of a quarter of an inch measured across the 

 frond. Dissepiments about the same in diameter as the 

 branches, usually placed at intervals of from one line to a 

 tenth of an inch apart.' Fenestrules oblong, rectangular, 

 nearly equal, from one line to one-tenth of an inch in 

 length by two-thirds of a line in width, nine in one inch 

 measured vertically, and twelve in the same space mea- 

 sured diagonally, placed nearly but not quite at the same 

 level in contiguous rows. Celluliferous face unknown. 



This species (Fig. 41) is most nearly allied to Fen- 

 estella laxa (Phillips), from the Carboniferous and De- 

 a. Portion of the poiyzoary of Fenestella V onian Kocks of Britain ; but it is readily distinguished 



magnified (Nich.), natural size ; o. a fragment . IT i,i/ i j.i_ 



of the same enlarged. From the Comiferous by the regular dimensions ot the tenestrules, their rectan- 

 gular shape, and their much smaller size. (The fenestrules 



Fig. 41. 



Limestone. 



