PLATE IX. 



Page. 



Fig. 1 . AvifULOPiNNA nbbraskensis 4.35 



A rather small specimen in which both valves are preserved nearly in place. 



Left valve seen from the side. The specimen is very imperfect, and restoration has been 



made as far as possible from growth lines. 

 Eico formation: Scotch Creek, Rico quadrangle (station 2342). 



Fig. 2. Avichlopinna nebraskensis 435 



Right valve of a much larger specimen than the preceding. Outline restored from the 

 lines of growth, showing a shape somewhat different from the small specimen, the 

 original of fig. 1. 

 Side view. 

 Rico formation: Scotch Creek, Rico quadrangle (station 2.S42). 



Fig. S. Monopteria alata 431 



The only specimen in the collection referred to this species. 



Shell seen from the side. 



Rico formation: Scotch Creek, Rico quadrangle (station 2342). 



Fig. 4. Allerisma terminale 437 



The type specimen upon which Hall's species was based. The obliquity of this specimen 

 is clearly the result of compression, and the species is, I feel little doubt, the same 

 which Meek and Hayden subsequently described as Allerisma subcuneatum. 

 Left valve seen from the side. The papillose surface which this specimen retains is 



present on well-preserved examples of A. subcuneatum. 

 Rico formation: Scotch Creek, Rico quadrangle (station 2342). 



Fig. 5. Allerisma terminale 437 



A right valve whose size is much smaller than is sometimes attained by this species. 



Side view. 



Rico formation: Scotch Creek, Rico quadrangle (station 2342). i 



Fig. 6. Allerisma terminale 437 



A small left valve whose size and proportions suggest that it may possibly be a distinct 



species or. variety. 

 Specimen seen from the side. 

 Rico formation: Scotch Creek, Rico quadrangle (station 2342). 



Fig. 7. Edmondia gibbosa 447 



A right valve preserved as an internal cast, and not very perfect. 

 Side view. 



Rico formation : Scotch Creek, Rico quadrangle ( station 2341 ) . 

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