PHYLOGENIC STAGE OF THE GASTROPODA 479 



Jour. Geol., Vol. XI, No. 5 Plate I 



11 



10 



Fig. 1, Scendla reticulata 1&\\\., after Walcott ; 2, Trybliditim barabiiense, Whitf., 

 Xj4; 3, Tryblidhan simile Whitf., X^z', 4, Tryblidium nycteis'2>\\\., Xj4\ 5> Tryblidium 

 retrorsum Whitf., X/^! 6, Hypseloconiis reacrvum Whitf., XK'> 7) Metoptoma orithyia 

 Bill., XK; %, SccEvogyra sweezeyi Whitf., X/^; (), Sccevogyra elevata Whitf., X/^; 

 10, II, and 12, Maclurea acuminata Bill., after Whitfield, X/^. 



