PLATE 2. 
Page 
Fig. 1. Lingula ceryx .. 5 
1. An imperfect valve in arenaceous rock. 
Fig. 2. Lingula desiderata . 6 
2 An imperfect valve enlarged to two diameters. 
Fig. 8. Lingula manni. 6 
3. A single valve of natural size. 
Figs. 4-6. Lingula nuda. .. 10 
4, 5, 6. Separate valves presenting the usual variety of form of this species. 
Fig. 7. Lingula punctata. 10 
7. Profile of a specimen retaining both’ valves in connexion. 
Fig. 8. Lingula ligea var. 8 
8. A specimen of this species from the Portage group, at Trumansburgh, N. T. 
Fig. 9. Lingula delia. 12 
9. A specimen of the natural size, showing the mark of a linear septum. 
Figs. 10, 11. Lingula densa. 11 
10. 11. A ventral and dorsal valve of the natural size. 
Fig. 12. Lingula leana. 9 
1'2. A ventral valve of the natural size. 
Fig. 13. Lingula maida. 9 
13. A specimen of the natural size. 
Figs. 14, 15. Lingula alyeata. 12 
14. An impression with the remains of the shell on the margin, showing the mark of a longitu¬ 
dinal septum. 
15. A larger individual; the impression in shale shows what appears to have been a triple 
medial septum. 
Figs. 16, 17. Dtscina tullia. 22 
16. Vertical view of a dorsal valve, natural size. 
17. Profile of the same. 
Fig. 18. Discina humilis. 16 
18. View of a ventral valve. 
