PLATE XLVI—Continued. 
Fig. 12. 
Fig. 13. 
Fig. 14. 
Fig. 15. 
Figs. 16, 
Fig. 18. 
Fig. 19. 
Fig. 20. 
Fig. 21. 
Fig. 22. 
Fig. 23. 
Fig. 24. 
Fig. 25. 
Fig. 26. 
Fig. 27. 
Fig. 28. 
Fig. 29. 
Fig. 30. 
Fig. 31. 
Fig. 32. 
Fig. 33. 
Fig. 34. 
Nucula yaricosa. 
Page 319. 
See Plate 93. 
A left valve, natural size. 
Hamilton group. Shore of Cayuga lake, N. Y. 
An enlargement from the preceding specimen. 
A right valve, natural size, with more prominent umbo and beak than the preceding. 
Hamilton group. Shore of Cayuga lake, N. Y. 
An enlargement from fig-. 14. 
17. Enlargements of left valves. 
An enlargement of a left valve with an unusual gibbosity of the umbo. 
Hamilton group. Slioi'e of Cayuga lake, N. Y. 
A left valve, unusually elongate from the beak to the post-basal extremity, enlarged. 
A right valve of the usual form of the species, enlarged. 
An enlargement from a specimen of unusual length from the beak to the post-inferior extremity. 
An enlargement of the cardinal area showing the fine crenulations of the hinge. 
Hamilton group. Shore of Canandaigua lake, N. Y. 
An enlargement from the surface of the specimen, fig. 19. 
Hamilton group. Shore of Cayuga lake, lY. Y. 
Nucula corbuliformis. 
Page 319. 
An individual, natural size. 
Hamilton group. Shore of Owasco lake, N. Y. 
A left valve of a larger individual. 
Hamilton group. Bellona, Yates Co., N. Y. 
A right valve, with the umbo more elevated than usual, partly from compression. 
Hamilton group. Bellona, N. Y. 
An enlargement from tig. 24, showing more distinctly the surface characters. 
A left valve, enlarged. 
Hamilton group. Shore of Skaneateles lake, N. Y. 
An enlargement of a left valve. 
Hamilton group. Shore of Cayuga lake, N. Y. 
An enlargement from fig. 25. 
A right valve, enlarged. 
Hamilton group. Bellona, Yates Co., N. Y. 
A right valve, enlarged to two diameters. 
Hamilton group. Ludlowville, N. Y. 
An enlargement of a left valve, which is more equilateral than the prevailing forms. 
Hamilton group. Near Tally, N. Y. 
An enlargement from fig. 26, showing a few crenulations on the posterior part of the hinge. 
