712 



GEOLOCY 



stages of deposition. The first known cuttle-fishes (sepeoids) also 

 appeared at this time. 



(3) Pelecypods flourished during 1 ho period ( Fi<;. is:',), a.nd look 

 on a markedly modern aspect, the oyster family taking the load. 

 Gastropods were abundant in some quarters, but singularly absent 

 in others. Existing genera were represented. 



Fig. 481. A GROUP OF JURASSIC AMMONITES, -h, Coron/'r, m* 

 (Brug.), a lateral and ventral view of one of I lie An'tti<l<r; c, 

 xnlmrmatum (Young); d, Perisphinetes tiziani (Oppd ) ; e, I\< incchi 

 Stcinm. 



