2b YORKSHIRE TYPE AMMONITES Dec. 



2. AMMONITES RIPLEYI, Simpsox 

 (Plate II) 



Original Description 

 " II. A[mmonites] Ripleyi. [M. Simpson, 1843, p. 11.] 

 [" I. Without a dorsal keel or furrow. 

 " a. No spines." p. 7.] 



" Depressed ; volutions 5 or 6 exposed ; radii straight, diverging, 

 obtuse, bend towards the aperture in passing over the back ; a row of 

 minute tubercles on the outer margin of the whorls ; aperture quadrate ; 

 diameter Jy inch. 



" This rather resembles the last [A. trivialis], but the whorls diminish 

 less rapidly, and are flatter on the sides ; the tubercles are much more 

 regular, and are continued upon the inner whorls ; the radii also, in 

 passing over the back, do not form angles as in A. trivialis. This is also 

 from the Lower Lias at Robin Hood's Bay." 



Additional Details 

 Simpson, 1855, p. 44, after "back" in first par., adds, "where 

 they are obsolete " ; omits " depressed " at beginning, and all second 

 par. ; 1884, p. 74 as 1855. 



Remarks 



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



The suture-line is similar to that of ^. regnardi, given by d'Orbigny : 

 L^ is similarly unequally tridactyloid ; but L^ is more oblique. 



The diameter of No. 106 in Whitby Museum is seven-tenths of 

 an inch. 



The genus is Uptonia, S. Buckman, 1898, 453 — family Polymorphidae. 

 The geological position is presumably ' Lower Lias y" 



Result 

 Uptonia ripleyi, Simpson sp. 1843. Charmouthian [jamesoni- 

 zone], Robin Hood's Bay, near Whitby. 



