22b YORKSHIRE TYPE AMMONITES Mar. 



22. AMMONITES ELABORATUS, Simpson 

 (Plate XXII) 



Original Description 

 " i68. A[mmonites] elaboratus. [M. Simpson, 1884, p. 128.] 



[" III. Keel between two furrows. 



" (n.) Furrows slight." p. 127]. 



" Depressed ; volutions six, exposed, prominent on the rounded inner 

 margin, outer whorl less than one-third the diameter, pinched towards 

 the back ; radii strong, sharp, regular, tending to form tubercles on 

 both margins, suddenly turn towards the aperture on the back, separated 

 by deep concave grooves ; keel much depressed, sharp, smooth ; aperture 

 quadrate ; diameter, two inches. M. L., a, Hawsker. 



" This belongs to the A. spinatus family, and is from the uppermost 

 bed of the Middle Lias on the Hawsker shore. It is highly finished 

 and well distinguished from A. solitarius by the prominence of the inner 

 margin of the whorls and the smooth keel. From the ribs rising on 

 both margins a slight hollow or groove is formed along the side of the 

 whorl. Whitby Museum, No. 302." 



Remarks 



Stages, conch, serpenticone ; periphery, 5 ; ornament, 5***. 



The carina is slightly crenulate ; the radii run far forward to join 

 the carina ; on the edge of the periphery they are almost tubercled 

 (bullate) ; on outer edge of margin, just before, is a papilla on each 

 rib ; and towards inner edge another bullate swelling — so that the 

 ornament is really 5***. 



Genus, Paltopleuroceras, S. Buckman, 1898, 453, — family Amaltheidae. 



Result 



Paltopleuroceras elaboratum, Simpson sp., 1884, Domerian, 

 spinatum zone, Hawsker, near Whitby. 



