EXPLANATION OF FIGURES.— PLATE 1. 



Page 

 Fig. 1. LlMQULA SPATULATA 13 



1 a. A specimen of the natural size. 



1 6. An enlargement of the specimen 1 a. 



Fig. 2. LiNOULA LIGKA 7 



2 a. The exterior of a valve, natural size. 



2 6. The interior of a valve which shows faint indication of muscular or vascular marking about 

 the middle of its length. 



Figs. 3, 4. LiNOULA MELIE 14 



3, 4. Show the extremes of form among a considerable number of specimens. 



Fig. 5. LlNQTTLA CUYAHOGA. 15 



5. A single valve of the natural size. 



Fig. 6. LiNGlILA PUNCTATA 10 



6 o. A young individual of the natural size. 



p b- An individual of the ordinary size, which is a little wider than usual. 



6 c. The interior of a valve. 



5 d. An individual from which the shell is nearly all exfoliated, showing the peculiar muscular 



impression.s illustrated in fig. 6 e, which is enlarged two diameters. It is probably 

 ' the ventral valye, 



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 int-erior characters should properly be separated from Lingula. 



Fig. 7. LiNOCLA PAL.a:F0RMI8 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 NEWBERRVI 25 



10 a. A dorsal valve of this species. 



10 4. A ventral valve with the shell nearly all exfoliated. 



11 a. A dorsal valve of this species. 

 11 6. A profile of the same. 



11 c. A dorsal valve of different form, but probably of the same species. 



Figs. 12, 13. DisciNA neglecta 24 



12. An impression of the dorsal valve with a part of the shell remaining in the centre, and 



showing the muscular impressions. 

 18. From a gutta-percha cast made in the impression of a dorsal valve. 



