PLATE LI. 



PAGE. 

 Figs. 1 to 3 CAMEROCERAS PROTEIFORME Hall 777 



(See alHO plates LVIII, LIX, uc, uci, LXU.) 



1 The exterior of a sipho, showing the short septal funnels. 



2 The same specimen longitudinally sectioned and showing one, and traces of a 



second siphonal sheath. 



3 Portion of a larger siphon; showing more distinctly the septal funnels. Trenton 



limestone, Cannon Falls, Minn. 



Fig. 4 CAMEKOCERAS, sp? 777 



4 A specimen whose specific relations are uncertain, having a narrow, cylindrical 



sipho and relatively short septal funnels. Cannon Falls, Minn. 



Figs. 5 to 7 CAMEROCERAS, sp 780 



5 and 6 Two views of a subtriangular sipho with broad septal funnels. Its specific rela- 

 tions are not known. 

 7 Outline section of the same. From the Trenton limestone, Zumbrota, Minn. 



