PLATE 51. 

 Fig. 1. 270. 23. Orthoceras amplicameratum. (Pag. 205.) 



1 a, b. Parts of tho same individual, preserving a large portion of the outer chamber, with an c(|ual length of 



the septate part of the tube. 

 I c. A transverse section of the specimen, at the upper extremity of 1 a, showing the excentric position of the 



siphuncle. 

 \ d, e. A. fr^ment of another specimen, showing the same distance of the septa and excentric position of the 



siphuncle. 

 1 /. A fragment of the septate portion of a much larger specimen. 

 1 g. Transverse section of the same, showing the position of the siphuncle. 



Y\g.2a,b. 279. 11. Endoceras arctiventrum. (Pag. 217.) 



Fig. 3. 280. 12. Endoceras angusticameratum. (Pag. 218.) 



