2X1) YORKSHIRE TYPE AMMONITES Mar. 



28. AMMONITES AUREOLUS, Simpson 

 (Plate XXVIII) 



" 172 Afmmonites] aureolus. ! M. Simpson, 1855, p. 94]. 



["III. Keel between two furrows." p. 90. 



" b. Furrows distinct." p. 93.] 



" Volutions 8, exposed, outer whorl less than \ the diameter, sides 

 regularly rounded ; radii numerous, nearly straight, sharp, not equal 

 to the intervening concave furrows, terminate on the outer margin of the 

 whorl ; keel rounded, depressed, between two slight furrows ; aperture 

 roundish ; diameter i inch. 



" This ammonite, on the side, greatly resembles A. aureus, and the 

 radii in places have a tendency to form two slight tubercles. The cast 

 is smooth, and of a golden colour. 



" The shell is thin, smooth, and brownish, without any appearance 

 of striae ; the ramifications of the septa are very simple and distant, 

 at irregular intervals of two or three radii. — L.L. ; R. H. Bay ; Mr. 

 Clarkson's Col. 



Additional Details 



Simpson, 1884, 134, adds to first par. : " L.L. ; 15, R. H. Bay." Adds 

 to second par. : " On comparing a description I wrote of a specimen 

 I received of Mr. Bean, labelled A. finitimis, I find it identical with 

 the above. I also believe that Blake's A. spiratissimus is the same as 

 my A. aureolus. They are all from the same bed, and are strongly marked 

 to the very centre." 



Remarks 



Stages, conch, serpenticone ; periphery, 4 ; ornament, 4 passing 

 to 5. The carina in the last half whorl becomes distinct though feeble, 

 with small depression each side of it. The small tubercles on outer end 

 of ribs can be seen ; but there is nothing of the kind on inner area. 



Genus Echioceras, Bayle, 1878 ; family Hildoceratidae perhaps ; 

 see A. exortus, 19. Geological position as given by Simpson, L.L. 15 

 [oxynotum zone] seems low. 



Result 



Echioceras aureolum, Simpson sp. 1855, Sinemurian, oxynotum 

 zone [? Charmouthian, raricostatnm zone], Robin Hood's Bay, near 

 Whitby. 



