Figs. 1-5. 
PLATE 56. 
Leiorhynchus MYSIA ... 
Page 
857 
(The figures of this species are all enlarged to two diameters.) 
1-3. Dorsal, ventral and profile views of a specimen of the ordinary size and characters of 
the species. 
4. Dorsal view of another individual, having a less prominent beak and duplicate plications. 
5. Dorsal view of an unusually large specimen, with sloping cardinal line. 
Figs. 6-21. Leiorhynchus limitaris. 856 
6-8. Dorsal and ventral views, and profile of a specimen of the usual form and size of those 
from the limestones in the Marcellus shale of Schoharie Co., N. Y. 
9. Ventral view of another specimen, with fewer plications in the sinus. 
10-12. Dorsal, profile, and front views of a somewhat larger specimen. 
13, 14. Profile and front views of a very gibbous form, having numerous plications. 
15-19. Dorsal ventral, profile, cardinal and front views of an unusually large and broad 
individual. 
20. Front view of a very gibbous form, which is abruptly elevated in front and having only 
three plications in tiie sinus. 
21. Dorsal view of a flattened specimen, from the thinly laminated black shales. 
Figs. 22-25. Leiorhynchus dubius... 364 
22. Dorsal view of a specimen, with a slightly elevated mesial fold. 
23-25. Dorsal, ventral and profile ❖iews of a specimen, with a more distinctly elevated 
mesial fold, and stronger plications. 
Figs. 26-40. Leiorhynchus multicosta... 358 
26. Dorsal valve of a young individual. 
27. Dorsal valve of a larger individual. 
28. Dorsal valve of a specimen of medium size. 
29. Cardinal view of a gibbous specimen. 
30. Dorsal view of a crushed individual of ordinary size. 
31. 32. Yentral valves of elongated specimens, showing considerable variation in the plications. 
33. Cast of a dorsal valve of unusually large size. 
34, 35. Dorsal and ventral views of a young and much elongated specimen, from Widder, C. W. 
36 - 40. Dorsal, ventral, profile, cardinal and front views of a full grown and well preserved 
individual, from the Hamilton shales of Canada. 
Figs. 41-43. Leiorhynchus iris. 360 
41 - 43. Dorsal, ventral and profile views of the specimen described. 
Figs. 44-49. Leiorhynchus quadricostata... 357 
44. Dorsal valve of a crushed and flattened individual of small size. 
45-48. Views of dorsal valves of this species, showing gradations in size. 
49. Ventral valve of a large individual. 
