392 A. S. Foord — A^nmonites in the British Museum. 



be compared with Turrilites in this respect. Bhabdoceras is straight 

 like Baculites. All are from the Alpine Trias. ' 



The PiNACocERATiD^ Contain the large species known as 

 Pinacoceras Metternichi, from the Keuper of Hallstadt, in Upper 

 Austria. (Wall-case 12.) 



Fig. 1. 



Traclnjceras Aon, Miinst. (Alpiue Trias. 



The extreme delicacy of the ramifications of the sutures in this 

 species excels that of any other Ammonite known. The leaf-like 

 terminations of the sutures in the PnYLLocERATiDiE are the dis- 

 tinguishing feature in this group ; they are well seen in the typical 

 species Phylloceras heterophyllum, Fig. 3. (Wall-case 11.) This 

 family began in the Trias, but it extended through the Jurassic 

 into the Cretaceous. 



Fig. 2. 



Ceratites nodosus, De Haan. (Muschelkalk.) 



The suture-line is again the most important feature in the family 

 next in order, viz. the Lytoceratid^, for it supplies the justification 

 for connecting together an assemblage of genera differing widely in 

 external shape. The family begins in the Trias, and is largely 

 represented in the Jurassic and Cretaceous rocks. One of the most 



