PLATE 2 8. 



I'M-,' 



Fig 1. Micrabacia Americana — - 1 



l.«. A view of the under side, natural size (type-specimen). 



1. h. The same, magnified. 



I.e. A vertical section, in outline, a little more magnified. 



1, tl. A partial side view, magnified to show cremated edges of the septa, etc, 



Fig. 2. Microstizia millepunctata 4 



2, a. A Fragment, natural size (type-specimen). 



2, b. The same, magnified. 



-', < . One of the bars, or dissepiments, between the fenistrules, highly magnified to show the 

 numerous, crowded, minute punctures. 

 Fi<;. 3. Websteria cretaoea :i 



3, a. Some of the branches, natural size (type-specimen ). 

 3, //. A bifurcating portion of one of the same, magnified. 



3, c. A simple branch, a little more magnified. 



Fig. 4. Ostrea PELLUCIDA I.'i 



A, a. Au under-side view of lower valve, showing its large scar of attachment (type-specimen). 



4, b. Interior of same. 



Fig. ■">. Ostrea (Gryph.eostrea ? ) subalata ir> 



An upper side view of the two valves united (type). 

 Fig. (i. Chenella elegantui.a 75 



6,a. Exterior of a right valve, natural size (type-specimen). 



li. h. Anterior of same. 



li. e. Exterior of right valve, magnified to show the fine radiating stria' more distinctly. 

 Fir. 7. Vulsella Galpiniana ?:! 



T,(/. A left-side view of an internal cast. 



7, b. A dorsal view of same. 



Fni. 8. Vulsella attenuata 71 



8, «. A right-side view of a cast (type-specimen). 

 8, 6. Dorsal side of same. 



Fig. 0. Yoldia scitula 110 



A left-side view of the complete type-specimen, natural size. 

 Fig. 10. Yui.dia Evansi t ill 



In. a. A dorsal view. 



10, 6. A left view of the larger complete type-specimen. 



10, c. An internal east showing pallia] sinus and hinge-denticles. 



Fig. 11. Ptehia (Oxytoma) Nebrascana 34 



Left valve of a medium-sized specimen. 



Fig. 12. Pteria ungciformis, vdr. subglbbosa :;:t 



An internal cast of a left valve (typo of variety). 



Fig. 13. Nucdla cakcellata 102 



13, (i. A left-side view, natural size, of the perfect type-specimen. 

 13, b. Dorsal view of a partly exfoliated specimen. 

 13, c. Left-side view of 13, a. magnified. 

 13, rl, e. Two views of an internal cast. 



