CANADIAN FOSSILS. 45 



Orbitolites), there are no superficial cells proper, although the cavity 

 has swelled out and been extended at the terminations of the columns 

 above and below, so as to give the appearance of a superficial stra- 

 tum. It will be seen by the description that this form most nearly 

 illustrates our fossil. 



R. OCCIDENTALIS, N. Sp. 



Plate X. Figs. 1-7. 



Synonym. — R. Neptunii? Hall, Palaeontology of New York, vol. i. 

 page 68, plate 24, figure 3. 



Specific character. — R.magnus, 5-6,pollicaris, vix infundibulatus, crassus, 

 cettulis verticalibus rectis cylindricis, apicibus supra rotundatis co?ivexis, 

 subter ylanis, rhomboideis granulatis. 



Discoid, from four to six inches broad, and from half an inch to an 

 inch in thickness ; the limb gently convex above, but rather sud- 

 denly indented and cup-shaped in the middle, from which the rows 

 of cells radiate in curved lines, crossing like the engine-turned orna" 

 ment of a watch. The thickness of the disk near the centre is but 

 little, but this increases rapidly towards the margin, becoming in 

 some cases half an inch thick at twice that distance from the centre. 

 The cavities of the cells themselves (in the fossil filled up with silex) 

 are not above a line and a half broad in the largest specimens. 

 They are rhomboidal on the lower surface (figure 5) ; on the upper 

 (figure 3) they terminate in a convex boss and have wide openings 

 between, but are connected by four lateral processes with the 

 adjoining cells. 



A cross section, as in the right-hand portion of fig. 1 (fig. 6c) shews 

 the columns round (a) and with interstices nearly equal to their own 

 diameter, and a lateral view (figure 6) shews the columns with their 

 bases (a) expanded, so as to leave but narrow linear interstices on 

 the lower surface*. At a short distance above this they give birth 

 to four connecting processes or stolons (c), as above described. 

 The columns are thence cylindrical, and nearly their own diameter 

 apart. In one of the specimens there are several intermediate small 

 connecting stolons along the columns (figure 4a), and this is impor- 

 tant in comparing the fossil with the recent Orbitolites. 



* Figures 1, 4, 5, 6, T, are reversed, being placed upside down on the plate. Figures 

 2, 3, shew the upper surface of the cup. 



