Ammonoidea — Ammonites, 



39 



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*' serpentmus zone," or Jet Ilock, which has yielded some of the GALLERY 

 finest and best preserved Ammonites of the Yorkshire Lias. 

 Of Inferior Oolite species, Ludwigia MurchisoncB and Oppelia suh- jq. 

 radiata may be mentioned. 



YiQ.IQ.—Grammoceras serpentinum,^c\i\o\^. Fig. Il.—Besmoceras ligattim,WOYh. 

 Upper Lias. Neocomian. 



The PuLCHELLTD^ (Cretaceous) are remarkable for the simplicity 

 of their suture-line, some resembling Goniatites, others Ceratitcs, 

 in this respect. They are considered to be true Ammonites, 

 descendants of the Jurassic Hakpocekatid^, but in a state of 



Fig. 72. — Stephanoeeras Blaydeni, Sby. Inferior Oolite. 



degeneracy. PulchelUa compressisaima (Lower Cretaceous) and Table- 

 Neololites Vihrayeanus (Upper Cretaceous) may be cited as ^*g®* ^^ 

 examples of this small group. 



The Haploceratidje, ranging from the Inferior Oolite to the 

 Middle Chalk, differ in many respects from the Haepoceratid^, 

 from which they branch off. The shell is generally thick, 



