PLATE III. 



PAnK. 



OrTHOCERAS TURBIDX'M 100 



Fi;i. 1. Yiew of the specimen desciibed, showing the ri'malns of longitudinal ridgep. 



Orthoceras Duseri 1)7 



Fig. 2. View of tlio perfect specimen from which the species was described, allowing all the chaiac- 

 tei'fl of the shell except the outer chamber. 



3, Yiew of H septum, and a single bead of the siphnncle, as seen in a section of the upper part 



of the specimen fig. 2 by breaking. 



4. Enlargement of the surface, showing the peculiar reticulated texture of the surface under a 



magnifier, when well preserved. 



CtOMPHOCERAR EOS 100 



Fig. 5. View of the specimen described, showing the outer chamber and several septa. 



