PALEONTOLOGY. 

 PLATE IX. 



Page. 



Endocostka typica Wliitf 403 



Fig. 1. View of a cast of a left valve of medium size, with the ridge extending to the edge 



of the cast. 

 Fig. 2. View of a partially exfoliated right valve, showing the impression of the ridge in 



the upper part and the substance remaining below, but easily traceable. 

 Fio. 3. View of a larger right valve, retaining about one-half of the substance of the ridge, 



the margin of the remaining portion being very perceptible. 

 Fig. 4. View of the left side of a still larger specimen, partially exfoliated, showing the ridge 



less developed. A part of the shell here remains, which, if removed, would 



make the impression still deeper. 

 Fig. 5. Cardinal view of the specimen. Fig. 4, showing the right valve the largest. 

 Fig. 6. Outline cardinal view of the hinge of a small individual, showing the area after 



the fibrous coating has been removed. 

 Fig. 7. View of the interior of the left side as obtained by a gutta-percha impression from 



the natural cast. 



I.VOCERAMU8 BARABIKI 398 



Fig. 8. View of a specimen of the form usually referred to this species, from this locality, 

 showing the muscular impressions, anterior and posterior. 



IxocERAMUS siMPSONi T Meek 395 



Fig. 9. View of a young, slightly distorted specimen, referred with doubt to this species. 



IXOCKRAMUS fragilis H. & M 390 



Fig 10. View of a large left valve, having the characters of the type of this species. 



iNOCERAMUS ALTUS M. &. U 391 



Fig. 11. View of an imperfect left valve of this species. 



InOCERAMUS TENUILINEATUS H. & M 400 



Fig. V2. View of the right side of a large, well formed specimen of this species, preserving 



a rim of the outer fibrous coating around the margin of the valve. 

 Fig. 13. Anterior profile view of the same, showing the great rotnndity of the shell. 



