266 SMITH. 



EXPLANATION OF PLATE D. 



Schloenbachia oregonensis Anderson. 

 Development of the septa. 



Fig. I. Septum at seven-eighths whorl; diameter 0.73 mm.; glyphioceran 

 stage ; paranepionic. ^-. 



Fig. 2. Diameter 1.70mm.; gastrioceran stage; twowhorls; paranepionic. ^. 



Fig. 3. Diameter 2.50 mm.; paralegoceran stage; two and one-half whorls; 

 paranepionic. ^^-. 



Fig. 4. Diameter 3.00 mm.; Styrites stage; two and seven-eighths whorls; 

 ananeanic. -*j^. 



Fig. 5. Diameter 3.80 mm. ; three and one-eighth whorls ; Parastyrites stage. -^^. 



Fig. 6. Diameter 4.86 mm.; three and one-half whorls ; neanic. ^. 



