HXl'LANATION OF PLATE XLVIII. 



Trigcinia thokacica Mortnn p. 460 



1-2, Views of a l^ft and ri right val\'e 



Mai-sliulltnz^'ii ilay'iiiai'l ; near Si^'i'desbovo. (Z//). 

 3-4, Two views of an inlcrnal cast. The type of T. iiiortoni 

 Whitf. 



A'uvcsiiik mar!; frcchnld. 



TuiGoxiA EUFAULfixsis Gabb p. 462 



5. View of an internal cast. 



]l'cnonah sand; near Marlboro. [ise>). 



6. View of an internal cast. 



Merelianl-eille elay-inail: Lenola. (16^). 

 7-S. Two \-ic\vs nf a complete individual from Alabama. (Coll. 

 U. S. Nat. IVlns.) 

 9-10. Internal and external views of a left valve from Alabama. 

 (Coll. U. S. Nat. Mus.) 



Tkigonia k, mmei.i n. sp p. 4(36 



11-12. Views of Iwn left vah-es, plaster casts taken from n.atural 

 moulds of llie exterior. 



Red BanI; sand; Shreiusbury Rk\-i-, (116). 



Tkigonia cerui,i,\ Whiliield p. 464 



13. View of a left valve from the l\'pe locality. 



Tintou beds; Beers Hill Cnt. il-'9°). 



97S 



