78 BeecJicr and Scfniclicrt B radii al Supports. 



Figure 11. A little more advanced stage, showing- increased length of 

 connecting band. X 12. Specimens figures 7-11 are from 

 the Trenton shales, St. Paul, Minnesota. 



12. A looped stage, with broad, curved, descending branches and 

 more slender transverse band. X 6. 



13. The same; profile. X 6. 



14. A later stage, showing more slender loop. X <>. 



15. A specimen showing curved, diverging, descending branches, 

 long transverse band, and two projections of the lamella 1 , 

 which are the beginning of the spiral cones. X 6. 



16. A subsequent stage in which the lamella? are more extended 

 and ventrally and inwardly curved. X (> 



17. The same ; profile. X 6. 



18. A young individual in which there are about one and one- 

 half turns to each spiral. X 6. 



19. The same ; profile. X 0. 



20. The brachial supports in a mature specimen. X 0. The 

 specimens figures 12-20 are from the top of the Trenton, 

 Frankfort, Kentucky. 



21. The spirals and loop in a Canadian specimen of (Anazyffa } 

 nra recurvirostra. (After Davidson.) X >. 



22. The spirals and loop in (Halllna =) Zygospira Mtjf'or<I! \V. and 



S. Trenton, Tennessee. X (>. 

 23. The spirals and loop in (Jlalllna ) Zygospira ulcolli-lli YV. and 



S. Trenton, Minnesota. X 0. 

 24. The' spirals and loop in Zijgospira head! Billings. (After 



Hall.) X 2. 

 25. The spirals and loop in Zijgospira modesta Say. (After Tin 11.) 



X 2J. 

 26. The same. (After Davidson.) X '!'.. 



