EXPLANATION OF FIGURES.—PLATE 1. 
Page 
Fig. 1. . Lingula spatulata.. 13 
1 a. A specimen of the natural size. 
1 b. An enlargement of the specimen 1 a. 
Fig. 2. Lingula ligea.. 7 
2 a. The exterior of a valve, natural size. 
2 b. The interior of a valve which shows faint indication of muscular or vascular marking about 
the middle of its length. 
Figs. 3, 4. Lingula melie. 14 
3, 4. Show the extremes of form among a considerable number of specimens. 
Fig. 5. Lingula cuyahoga...... 15 
5. A single valve of the natural size. 
Fig. 6. Lingula punctata. 10 
6 a. A young individual of the natural size. 
6 b. An individual of the ordinary size, -which is a little wider than usual. 
6 c. The ihterior of a va'lve. 
6 d. An individual from which the shell is nearly all exfoliated, showing the peculiar muscular 
impressions illustrated in fig. 6 e, which is enlarged two diameters. It is probably 
the ventral valve. 
6 /. Another individual which shows the muscular impressions of a little different form, with a 
longitudinal depression. It is probably the dorsal valve. 
6 g. Is an enlargement of the surface showing the texture of the shell. 
Shells having these interior characters should properly be separated from Lingula. 
Fig. 7. Lingula pal^formis. 8 
7. A specimen (probably the ventral valve), natural size. 
Figs. 8, 9. Lingula exilis. 7 
8. A specimen, natural size, with the beak imperfect. 
. 9. A more convex individual which may belong to this species. 
Figs. 10, 11. Discina newberryi. 25 
1,0 a. A dorsal yalye of this species. 
10 b- A ventral valve with the shell nearly all exfoliated. 
11 a. A dorsal valve of this species. 
11 b. A profile of the same. 
11 c. A dorsal valve of different form, but probably of the same species. 
Figs. 12, 13. Disciija neglecta. 24 
12. An impression of the dorsal valve with a part of the shell remaining in the centre, and 
showing the muscular impressions. 
13. From a gutta-percha cast made in the impression of a dorsal valve. 
