'^ 



PLATE 51. 



Fig. 1. 270. 23. Orthocekas amplicamehatum. (Pag- 205.) 



1 a, b. Parts of the same individual, preserving a large portion of the outer chamber, with an equal length of 



the septate part of the tube. 

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



siphuncle. 

 I d,e. A fragment 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. 



Fig. 2 a, b. ' 279. 11. Endoceras arctitentkum. (Pag. 217.) 



Fig. 3. 280. 12. Endoceras angusticaheratuk. (F^ig. 218.) 



