PLATE LIII. 



PAGE. 

 Figs. 1 to 3 CAMEBOCEEAS HENNEPINI, sp. nov 779 



(See also plate LII.) 



1 Longitudinal section of a small fragment through the sipho; showing a portion 

 of the thick continuous wall of the tube and the annulations formed at the 

 junction therewith of the septa. On one side the siphonal wall is but partially 

 retained. 

 2 and 3 Two views of the same specimen. 



Fig. 4 OBTHOCEBAS LESUEUBI, sp. nov 779 



(See also plates XLVII and i.\ . p 



A portion of a shell protruding from an internal cast of the siphon of Cameroceras 

 proteiforme. From the Trenton limestone at Cannon Falls, Minn. 



Fig. 5 CAMEBOCEBAS PBOTEIFOBME Hall 777 



(See also plates xi.vm, XLIX, i.. JA.) 



Longitudinal section of a siphonal cast enclosing two individuals of Orthoceras 

 or CWnocercw. Trenton limestone, Cannon Falls, Minn. 



