87b YORKSHIRE TYPE AMMONITES— II Nov. 



87. AMMONITES FASCIATUS, Simpson 

 (Plate LXXXVII) 



Original Description 

 "22. A[mmonitesJ fasciatus. [M. Simpson, 1855, P- 4 1 -] 



["I. Without a dorsal keel or furrow. 

 " a. No spines." p. 35.] 



" Depressed ; volutions exposed ; outer whorl more than J the 

 diameter ; radii annular, nearly obsolete ; striae annular, separated by 

 flat or slightly concave spaces ; aperture ovate ; diameter i£ inch. 



" The cast of the inside is smooth, with very obsolete radii, or 

 annular swellings, towards the aperture ; the striae resemble narrow 

 thin strips of paper, laid on so as to show one edge ; the aperture is 

 nearly a very regular ellipse of but little eccentricity. The inner whorls 

 of the only specimen I have seen are defective. I found it in the Jet 

 Rock at Hawsker Bottoms. U.L." 



Additional Details 

 Simpson, 1884, 70, adds to end of 1st par. U.L., v, 7 [U.L. Div. 7]. 



Remarks 



Proportions : 29, 36, 38, 33 ; platy-, pachygyral, latumbilicate. 



Stages, conch, serpenticone ; periphery, 1 ; ornament, 2. 



A damaged outer whorl, most of which is body-chamber, with no 

 suture lines visible. 



Ornament, rather broad depressed striae, which trend somewhat 

 backward after leaving the rounded, rather steep inner margin. Later, 

 towards end of whorl, are signs of rings like those of Am. nitidus, No. 86. 



Genus, Trachyly toe eras, now (II, vii), on the supposition that it is 

 the striate or prior stage corresponding to the inner whorls of Am. nitidus, 

 the ringed stage coming on later in this species. Family Lytoceratidae. 



Result 

 Trachylytoceras fasciatum, Simpson sp. 1855, Whitbian, exaratum 

 zone, Hawsker, near Whitby. 



