PLATE 56. 



Fig. 1. 271. 24. Orthoceras steigatum. (Pag. 205.) 



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



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



1 e. A portion of the surface of the last enlarged, showing the flexuous character ofjthe strise. 



1 (/. A large specimen, preserving but indistinctly the striaj. 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. 

 If,/. A fragment, showing five chambers, with a section of the same. 



Fig. 2. 17. 2. Orthoceras laqueatum. • (Pag. 206.) 



2 a. A fragment imbedded in compact limestone. 



2 6. A small fragment, showing the intermediate finer striffi. 



2 c. A portion of the surface enlarged. 



Fig. 3. 272. 25. Orthoceras laqueatum ? var. a. {Pag. 206.) 



Fig. 4. 286. 1. Cameroceras 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. 

 ■1 b. Another fragment, with the siphuncle still more extended. 

 ■1 c. Transverse section, showing the position of the siphuncle. 



