PLATE XXXV. 



PAGE. 



Fig. 1. Orthoceras (Actinoceras) Turgido-nummut^atum, Foerste 538 



1. S. H. O. Collection of Geo. Caswell. 



Fig. 2. Orthoceras (Actinoceras) 539 



2. A form closely related to the last, but the septa more distant and the siphuncle more 



elongated. S H. O. Collection of Geo. Caswell A second specimen in my own 

 collection shows a smooth surface. 



Fig. 3. Orthoceras (Eu- Orthoceras ?) virgtcatum? Hall 534 



H. The specimen figured lesembles one identified by us on an earlier plate as this spe- 

 cies, in having the same distant septa; but the siphuncle is wider, 1.1 mm. ap- 

 proaching in this respect the wider siphuncle of O. ignotum. S. H. O. Collection 

 of Geo. Caswell. 



Fig. 4. Orthoceras (Actinoceras) 538 



4. A form closely related to O. lata-nummulatum, but the rate of expansion of the shell 



seems to be much greater; a, lateral view-, b, view from below showing eccentric 

 siphuncle; c, a section showing the large siphuncle. S. H. O. Collection of Geo. 

 Caswell. , 



Fig. 5. Orthoceras (Eu-Orthoceras) Hanoverense? Foerste 543 



5. See text. S. H. O. Collection of Geo. Caswell. 



