1899] Lambe — Canadian Paleozoic Corals. 245 



Corallum forming laminar or discoidal expansions, composed 

 of confluent corallites whose calyces open on the surface with 

 scarcely any line of demarcation between them ; reaching a 

 breadth of 9 cent, and a thickness of between 2 and 3 cent. 

 Calyces, varying in width from 8 to 12 mm., flat or shallowly 

 concave in the marginal area, with a circular, elevated rim sur- 

 rounding a central pit 3 or 4 mm. in diameter from which 

 radiate the septa as narrow convex ribs having a maximum 

 breadth of about 5 mm. The elevated rims surrounding the pits 

 stand, in some specimens, much more prominently above the 

 surrounding sunken cal)xinal extension than in others, whilst at 

 times they develop into salient, conical projections with the pit 

 forming an excavation at the top. Lateral junction of contiguous 

 calyces sometimes very slightly raised, more often seen as a 

 plane surface in which no dividing line is apparent. Septa 

 averaging thirty in number: as in other species of the genus, 

 lamellar and continuous vertically in the vicinity of the central 

 pit, converted on the flat calicinal margin into surface ribs that 

 join those of neighbouring calyces ; of two orders, alternating 

 with each other within the pit, the primai ies reaching the centre 

 or leaving a narrow, circular smooth spot at the centre, the 

 secondaries not continued beyond the sides of the pit. As in A. 

 pentagomivi, Goldfuss, a coalescence of the inner septal ends in 

 sets of twos and their continuance as single septa is often 

 observed. Double rows of pore-openings are present in the 

 septal ridges. The dissepimcntal and vesicular structure is 

 similar to that of A. petitagomun only proportionately smaller. 

 Small flat tabulae occur in the centre of the visceral chamber. 



Locality and formation. — Five miles west of Chicotte River, 

 Anticosti, J. Richardson, 1856; Owen Sound, Out., J. Townsend, 

 1874 to 1883 ; north end of Lake Temiscaming, Que., R. Bell, 

 1887 ; Niagara formation. 



Arachnophyllum EXIMIUM, Billings, sp. 



Strombodes eximius, Billings. 1866. Geol. Surv. Canada, Cat. 

 Silur. Foss. Anticosti, p. 93. 



