PLATE XX jr. 

 Aphyllostylus gracilis (page 279). 



Figure 1. Small piece of Silurian limestone from Stonewall, Manitoba, shewing a 

 longitudinal section of part of the ooraUum of a specimen of this 

 species, the nearly cylindrical shape of the coraUites, and the trans- 

 verse tabulae. 

 ■1 1 a. Portion of one of the corallites of the same specimen, six times the natural 

 size, to shew the septal spines on the surface of the interior. 



PeTRATA (PYGMiEAl VAR.) OGCIDENTALIS (page 291). 



Figure 2. Summit of a large specimen of this coral, as exposed on the weathered 

 surface of a small piece of Silurian limestone from the Grand Rapids 

 of the Saskatchewan. 



II 3. Similar view of a smaller specimen, on the same piece of limestone. 



II 4. Side view of another small specimen, from the Grand Kapids, shewing the 

 exterior of the coraUum, apparently minus the epitheca. 



II 5. Longitudinal section of a small specimen, exposed on the weathered sur- 

 face of the same piece of limestone as the originals of figs. 2 and 3. 



Ph^nopora Keewatisexsis (page 268). 



Figure 6. The type and only known specimen of this species, a fragment of a zoari- 

 um, from the Silurian limestone on a small island in the northern 

 Sutton Mill Lake ; twice the natural size. 

 II 6 a. Section of a portion of the same specimen ; six times the natural size. 



Trimbeella Ekwanexsis (page 249). 



Figure 7. Outline of a nearly perfect pedicle valve of a shell of this species, from the 

 Silurian rocks of the Ekwan River, slightly restored, and reduced in 

 size. The vertical line on the right shews the actual length of the 

 valve. 

 From a drawing by Mr. C. F. King. 



Stropheodonta acanthoptera (page 285), 



Figure 8. Ventral view of a specimen of this species, shewing the exterior of -the 

 whole of the convex ventral \ alve. The drawing was made from a 

 wax impression of a natural mould of the exterior of a ventral valve, 

 on a loose piece of limestone picked up on the beach on the north-east 

 side of Lake Winnipegosis by Mr. T). B. Bowling in 1888. 

 1. 9. Another specimen of the same species from the Silurian limestone at Long 

 Point, Winnipegosis. collected by Mr. .J. B. Tyrrell in 1889. 

 Both figures of this species are from drawings by Mr. L. M. Lambe. 



