PLATE XLIX. 



Orthoceras Lambtonense (page 404). 



Figure 1. Side view, in outline, of a cast of the interior of the shell of 

 a specimen of this species, collected ne;ir Thedford 

 by Mr. Kernahan and now in the Museum of the 

 Survey. 



Figure la. Outline of a transverse section of the same, shewing the 

 almost central siphuncle. 



