1884.] NATURAL SCIENCES OF PHILADLLPHIA. 55 



species. The acicular sulci which terminate the sinus in the 

 siphonal or median lobe do not appear in Waagen's drawing, but 

 as this is done on a small scale, the feature in question may have 

 been overlooked. In either case the septal plication is about 

 equally simple or primitive, and indicates a passage by which a 

 transition is effected from the more complicated forms to the still 

 simpler Goniatite. The discussion of the relationship existing 

 between the A. antiquus and certain Goniatitic forms described 

 by De Verneuil and Karpinsky from the sandstone of Artinsk, 

 equally applicable in its reference to the American species, is 

 fully set forth by Waagen {loc. cit.). 



