PLATE VIII. 



Page. 

 Fui. 1. AVICULOPECTEN OCCIDENTALIS ^ 414 



Internal cast of a right valve referred to this species. 



Specimen seen from above. 



Rico formation: Silver Creek, Rico quadran0e.( station 2347). 

 Fig. 2. Aviculopecten sp. a 417 



Internal cast of a left valve, somewhat enlarged. 



Specimen seen from above. 



Hermosa formation : Ouray, Colo, (station 2194). 

 Fig. 3. Aviculopecten ? interlineatus 416 



A right valve belonging to this species. 



Specimen seen from above. 



Hermosa formation: Ouray, Colo, (station 2194) . 

 Fig. 4. Pseudomonotis kansasensis 428 



A left valve of the type referred to this species. 



Specimen seen from above. 



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

 Fig. 5. Pseudomonotis equisteiata 428 



A specimen representing the type referred to this species. 



Shell seen from above. 



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

 Fig. 6. Myalina sub(1UADrata? 424 



Left valve showing one variety of shape assumed by the fossils from Colorado. 



Specimen seen from above. 



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

 Fig. 7. Myalina subquadkata? ^ 424 



A left valve of different shape from the preceding but associated with it. Possibly these 

 two shells are not really conspeciflc. 



Specimen seen from above. 



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

 Fig. 8. Myalina wyomingbnsis 422 



A small left valve. 



Specimen seen from above. 



Rico formation: Scotch Creek, Rico quadrangle (station 2340). 

 Fig. 9. Myalina wyomingensis 422 



A larger left valve of a somewhat different shape from the preceding. 



Specimen seen from above. 



Rico formation: Scotch Creek, Rico quadrangle (station 2340). 

 508 



