FIGURE Gi. Terebrataliform stage, with ascending branches attached 

 to ends of descending branches. 



FIGURE Hi. Final adult condition of Macandrevia cranium Miiller; 

 showing absorption of septum and connecting bands from descending 

 branches. 



FIGURE Ha. Adult stage of Macandrevia tenera Jeffreys. 



Ontogeny of Dallina septigera Loven 



FIGURES A, B, Ci. Stages of growth common to all the genera 

 of Dallininge. 



FIGURE Da. Late platidiform stage. 



FIGURE Ea. Ismeniform stage. 



FIGURE F2. Muhlfeldtiform stage. 



FIGURE Ga. Terebrataliform stage. 



FIGURE Hs. Adult Dallina septigera Love'n. 



FIGURE H4. Dallina Rapliaelis Dall. 



FIGURE H5. Dallina floridana Pourtales. 



FIGURE He. Dallina Grayi Davidson. 



FIGURES Ca, Ds, Es, Fs. Ontogeny of Muhlfeldtiasan guinea Chemnitz. 



FIGURE Gs. Terebratalia coreanica Adams and Reeve; adult structure. 



FIGURE F4. Muhlfeldtiform stage of Laqueus californicus Koch. 



FIGURE G4. Adult Laqueus californicus Koch ; showing connecting 

 bands from ascending and descending lamellae. 



FIGURE Gs. Laqueus pictus Chemnitz. 



FIGURE Ge. Trigonosemus elegans Koenig; a Cretaceous representa- 

 tive of the Terebratalia structure. 



FIGURE E4. Ismenia furcata Sowerby; Jurassic. 



FIGURE E5. Ismenia Buckmani Moore ; Jurassic. 



FIGURE Cs. Platidiform stage of Dallina Jloridana Pourtales V 



FIGURE C4. Adult Platidia anomioides Scacchi. 



MORPHOGENY OF MAGELLANIINvE (PagCS 293-295) 



Ontogeny of Terebratella dorsata Gmelin, and Magellania venosa Solander 



FIGURE A. Gwyniform stage. 



FIGURE B. Cistelliform stage. 



FIGURE Ca. Boucnardiform stage, with small ring on septum. 



FIGURE Ca'. Side view of same. 



FIGURE Da. Megerliniform stage; showing growth of ring, or 

 ascending branches. 



FIGURE Da'. Side view; showing growth of descending branches 

 as prongs on side of septum. 



FIGURE Ea. Magadiform stage ; showing completion of descending 

 branches. 



FIGURE Fa. Ufagaselliform stage; showing union of descending and 

 ascending branches. 



FIGURE Ga. Terebratelliform stage ; representing the finished type 

 of structure in Terebratella dorsata Gmelin. 



FIGURE Ha. Final stage of Magellania venosa Solander; produced 

 by resorption of the septum and connecting bands of the terebratelliform 

 stage. 



