PLATE 8. 



Page 

 Fig. 1. DiSCINA VANUXEMI. \&2 



1. Piofile view 



1 a. Dorsal view, sliowing the form of the shell. 



1 b. Enlargement of surface, showing the radiating and concentric strijv ( the latter are liot 

 strong enough in proiiortiou to the others) . 



Fig. 2 - 16. Strophodonta varistriata. 180 



2-6. Ventral valves, where the striae are nearly equal or alternating in size. 



7 &. 8. Individuals presenting some variety in surface characters. 



9. A young shell with salient liinge extremities, and strongly elevated stri.-e separated by 

 fascicles of liner striae between. 



5 a. The upper figure with this number is an enlargement of the surface of flg. 9. 



10. An individual with surface characters similar to the last, having the hinge extremities 



rounded, and the hinge line a little shorter than the greatest width of the shell below. 



11. Interior of a ventral valve. 



11 o ( by error 12 a) above last figure. An enlargement of the area and crenulations. 



12 & 12 a. Interior of ventral valve, and enlargement of area. 

 13. Interior of a ventral valve. 



14 & 16. Casts of the interior of the ventral valve, where the shell is but partially exfoliated. 



1.") & 1-5 a. The interior of a ventral valve, and enlargement of a portion of the same. 



16, at right hand of page. A portion of the surface much enlarged, showing the nearly equal 

 striae crossed by finer concentric lines. 



17 - 23. Spirifer vanuxemi. 108 



17, 18 & 19. Young individuals of this species. 

 20. Dorsal view of a medium-sized specimen. 



20 0, b, c. Ventral, profile and front views of tlie preceding s]M'cimen. 



21 & 2B. Dorsal views of larger specimens. 



22. Ventral view of another specimen of tliis species. 



2.3 a. Enlargement of the surface, showing the concentric lanielliE. 



