EXPLANATION OP PLATE XLII. 



Page. 



FIG . 1 Lima retifera 108 



Both valves. 



Carboniferous, Coal Measures . 



FIG. 2. .Entolium aviculatum 109 



2a. Interior aspect. 

 2b. Outside. 



Carboniferous, Upper Coal Measures. 



FIG . 3 Aviculopecten occidentalis 110 



Left valve . 



Carboniferous, Upper Coal Measures, 



FIG. 4. Pseudom onotis hawni (1) 



A finely-preserved shell. (Hare collection.) 

 Carboniferous, Upper Coal Measures. 



FIG 5. Aviculopecten sp .1 



. A medium- size! shell. (Mus. Mo . Geol. Sur ) 

 Carboniferous, Lower Burlington limestone. 



FIG 6 . Aviculopecten interlineatus 112 



Specimen with concentric markings well denned. 

 Carboniferous, Upper Coal Measures. 



FIG. 7. Aviculopecten fasciculatus 11$ 



A large example . (Hare collection.) 

 Carboniferous, Upper Coal Measures. 



