PLATE 29. 



Fig. 1. Gervillia recta 66 



1, a. A left-side view of the type-specimen, consisting maiuly of an internal cast, with some 

 of the inner layers of the shell remaining. [The extremity in front of the beats 

 being a little broken away.] 

 1, 6. A dorsal view of same, to show the unequal convexity of the valves. 



Fig. 2. Sph.eriola ? endotrachys 139 



A left-side view of the type-specimen, consisting of an internal cast. [Muscular impres- 

 sions represented too large and round, and the asperities of the interior too regular 

 and too scattering.] 



Fig. 3. Si-ii.EKioLA ? cordata 137 



:!,n. A posterior view of an internal cast, retaining portions of the shell (type-specimen). 

 3, ft. A right-side view of same. 

 '■'<, e. Left view of same. 

 Fig. 4. Ci'cuix.ea(Idon-eahca) Shumardi 86 



A left side view of a large specimen that has been drilled by some Gasteropod. 



Fig. 5. CiiculLvEa (Idonjsarca) Nebrascensis ". 88 



5,«. A right-side external view of a mature specimen. 

 ' C>, b. View of interior, hinge, and cardinal area of same. 

 Fig. 0. Cuculi./Ea (Idon.earca .') cordata 89 



6, </. A left-side view (type-specimen). 



6,6. A dorsal view, showing cardinal area, etc. 

 Fie. 7. Cyi>rina ovata 146 



7, a. Interior and hinge view of right valve of type-specimen. [For a more correct view of 



hinge, see wood-cut in text.] 

 l.b. An anterior profile view of same. 



7, c. An outside view of same. 



Fig. 8. Protocaudia subquadrata 17f> 



8, a. A right-side view of a mature specimen. [The creuulations of the basal margin, as well 



as those on the marks of growth, are too fine and carried too far forward in this 



figure.] 

 8, b. A ventral view of same, with the posterior marginal creuulations correctly represented. 

 8, c. A right-side view of a smaller specimen. 

 8, d. A posterior view of same. 

 8, e. A internal cast of a larger specimen, showing a small double pallial sinus, seen on casts 



of this species. 



