>iLi.iAM3] FOSSIL FAUxVAS OF THE ST. HELEN'S BRECCIAS 24S 



PLATE IIL 



Spirifeb pennatus Helena. 



FiGUBE 1. — Mold of interior of a brachial valve, showing the general form and 

 the narrow hinge-area and the articulating apparatus. 



Figure 2. — A small exfoliated brachial valve showing the groove in the median 

 fold. 



Figure o. — Fragment of shell showing the mucronate form of the cardinal ex- 

 tremity. 



Figure 4. — Molds of the interior of two valves showing the narrow mucronated 

 form. 



Figure 5. — Imperfect cast of a pedicle valve showing the flattened centre of the 

 median sulcus. 



Figure 6. — A fragment of brachial valve showing decided longitudinal groove in 

 middle of the fold. 



Figures 7, 8, 9. — Three imperfect specimens of brachial valve showing groove in 

 middle of the fold. 



Figure 10. — An exfoliated specimen of large sized pedicle valve in which the out- 

 line of the muscular scars may be faintly seen. 



Figures 11, 12, and 14. — Molds showing the evenly rounded form and the size 

 and frequency of the longitudinal plications.. 



Figure 13. — A mold of interior of a pedicle valve showing the hinge characters 

 and cavity of muscular scars. 

 All the specimens are from a block of linestone found at Côte St. Paul, be- 

 tween Montreal and Lachine, identified by its fauna and lithology with the St. 

 Helen's brecciated limestone 252.1. 



