PLATE 56. 



Fig. 1. 271. 24. Orthoceras STRiGATUid. (P&g. 205.) 



1 a. A young specimen, with the shell partially exfoliated ; a few of the septa being indistinctly visible. 

 1 6. A fragment, showing the shell in a considerable degree of preservation. 

 I e. A portion of the surface of the last enlarged, showing the flexuous character of^the stris. 

 I d. A large specimen, preserving but indistinctly the strisB. About twenty of the chambers are preserved, as 



well as a large part of the outer chamber. This specimen shows a small septate tube within the open 



extremity, but it is probably accidentally present. 

 i e,f. A fragment, showing five chambers, with a section of the same. 



Fig. 2. 17. 2. Orthoceras la^ueatum. • ( Pag. 206.) 



2 a. A fragment imbedded in compact limestone. 



2 b. A small fragment, showing the intermediate finer stria. 



2 e. A portion of the surface enlarged. 



Fig. 3. 272. 26. Orthoceras laqueatum? car. a. (Pag. 206.) 



Fig. 4. 286. 1. Cameeoceras trentonense. ( Pag. 221.) 



4 a. A fragment of the shell, preserving about three of the chambers, beyond which the siphon is extended to 



an equal distance. 

 4 b. Another fragment, with the siphuncle still more extended. 

 4 e. Transverse section, showing the position of the siphuncle. 



