244 ROYAL SOCIETY OF CANADA 



PLATE II. 



Spibifeb Montée alen sis. 



A series of the smaller specimens referred to this species, and some larger, 

 imperfect worn specimens from which the surface characters have been nearly 

 obliterated. 



FiGUEES 1, 2, 3, 4, 5. 7, 8, 10. — A series of youn? brachial valves, associated with 

 the larger specimens figui'ed on Plate I., referred to this species be- 

 cause the characters they present are indistinguishable from the corre- 

 sponding early stages of growth of the typical specimens. 



Figure 6. — Mold of exterior of a small brachial valve. 



Figures 9, 11, 12 and 13. — Much worn specimens exhibiting the prominent de- 

 velopment of the beak portion of the shell. 



Figures 14, 15 and 16. — Much worn and decorticated specimen which appear 

 to have been originally plicated as in the type specimens and to have 

 been smoothed by attrition before they were finally buried in the 

 sediments in which they were found. 

 All from the brecciated limestone block called 252.1 on St. Helen's island. 



