PLATE 42 



Rhipidomella musculosa Hall 



{See also plate 43) 

 Page 201 



I The interior of a dorsal valve 



2-4 Specimens representing the exterior and internal casts of ventral 

 valves 



5 Interior of a ventral valve. All the foregoing specimens are silica 



replacements of the shell 

 Grande Grlve limestone ; division i. Grande Greve 



Hipparionyx proximus Vanuxem 



Page 200 



6 Interior of a small ventral valve, regarded as pertaining to this species. 



Specimens of larger dimensions also occur at this locality 

 Grande Grtve limestone. Perce Rock 

 7, 8 Silica replacement of the dorsal valve. Interior and exterior views 

 9 The cardinal process viewed from behind 



10 Interior of a ventral valve 



11 Internal cast of a dorsal valve 



Grande Grlve limestone ; division i. Grande Greve 



336 



