55b YORKSHIRE TYPE AMMONITES May 



55. AMMONITES FLAVUS, Simpson 

 (Plate LV) 



Original Description 

 " 80. A[mmonites] flavus. |M. Simpson, 1843, p. 43.] 



[" With a keel on the back. 

 " a. Outer whorl broad." p. 31.] 



" Depressed ; volutions 3 or 4, inner ones | concealed, outer whorl 

 not J the diameter ; keel obtuse ; aperture ovate ; diameter £ inch. 



" This is not quite so much depressed as the last [A. buckii], and 

 the inner whorls diminish very little in thickness ; it is quite plane, 

 without radii or striae ; the septa are more distant than in the last, and 

 the lobes are less serrated, and not so numerous, it is also from the lower 

 lias at Robin Hood's Bay and has a metallic hue." 



Additional Details 



Simpson 1855, 86, omits " Depressed " ; adds in 2nd par. after 

 "striae" — "the shell is cracked ", and before "metallic" has "light." 



In this case " the last " would refer to A. aliaenus, but that may be 

 an oversight. 



Simpson, 1884, 123, the same as 1855 ; p. xxi, species entered in 

 Indurated Band 13. 



Remarks 



Stages, conch, almost oxycone ; periphery, 2c ; ornament, i. 

 Genus, Oxynoticeras, Hysitt (Gen. H), the species showing cunctative 

 palingenesis, particularly as regards ornament. Family, Arietidae, Hyatt. 



Result 



OxYNOTiCERAS FLAVUM, SiMPSON sp. 1843, Sinemurian, oxynotum 

 zone, Robin Hood's Bay, near Whitby. 



