PLATE 70. 



PHge 



Fig. 1. Orthoceras lonoicameratum. 343 



1. The siphuncle has been filled with crystalline matter, and the swollen portions are concave 

 above and beneath, indicating a thickening of the septum at its junction with tlie nar- 

 rower parts of the siplumcle. Some remains of the septa are still perceptible. 



Fig. 2. Orthoceras (sp. undetermined ). 



Fig. 3 a - d. Orthoceras kioidum. 344 



3 a. A fragment of this species, having the shell almost entirely removed. 

 3 6. A continuation of the same specimen. 



3 e. Transverse section, as shown in the line of fracture of fig. 3 6. 



3 d. Enlargement of the stria;. The position of the figure represents tlie striae in the reverse 

 of their natural relation, which is horizontal. 



