EXPLANATION OF PLATE XXXIX. 



Page 



FIG. 1. Meekella striatocostata ... 63 



la. Side view. 

 Ib. Dorsal aspect. 

 lc Ventral view. 



Carboniferous, Upper Coal Measures. 



FIG. 2. Streptorhynchus lens 67 



2a. Ventral aspect (Mus. Mo Geol. Sur.) 

 2b. Dorsal aspect of same. 



Carboniferous ? Louisiana (Kinderhook) limestone. 



FIG. 3. Strophomena alternata ,. 70 



An average size specimen. (Mus. Mo. Geol. Sur.) 

 Silurian, Trenton limestone. 



FIG. 4. Ortfiis tricenaria 60 



Ventral aspect. (Mns. Mo. Geol. Sur.) 

 Silurian, Trenton limestone. 



FIG 5. Platystrophia lynx 64 



Dorsal view. (Mus. Mo. Geol. Snr.) 

 Silurian, Trenton limestone. 



FIG. 6 Plectambonitesrhomboidalis,vSi,T 70 



Ventral aspect. (Rowley collection.) 

 Carboniferous, Lower Burlington limestone. 



FIG. 7. Strophodonta demissa. , 70 



7a. Dorsal aspect. 

 7b. Ventral view. 



Devonian, Hamilton limestone. 



FIG . 8 . Syntrilasma hemiplicata 76 



8a. Anterior view. 

 8b. Dorsal view. 

 8c. Ventral view. 

 8d. Side view. 



Carboniferous, Upper Coal Measures. 



FIG. 9 Leptcena sericea 75 



Interior side. (Mns Mo. Geol. Sur ) 

 Silurian, Hudson river shales . 



FIG . 10 Cyrtina acutirostris 89 



lOa. Side view (Mus. Mo. Geol. Snr ) 



lOb. Doraal aspect of same. 



Carboniferous'?, Louisiana (Kinderhoek) 1 mestone. 

 FIG. 11. Athyrit argentea 92 



lla. Ventral aspect. 



lib. Side view 



lie. Dorsal aspect. 



lid. Dorsal aspect . 



Carboniferous, Coal Measures . 



