47b YORKSHIRE TYPE AMMONITES Feb. 



47. AMMONITES INTEGRICOSTATUS, Simpson 

 (Plate XLVII) 



Original Description 

 " 40. Afmmonites] integricostatus. [M. Simpson, 1855, p- 4^-] 

 I" I. Without a dorsal keel or fun-ow. 

 " a. No spines, p. 35.] 



" This resembles A. gagateus, but it is more depressed, and the 

 whorls are more slender, very prominent on the back, and separated 

 by wide concave spaces ; the aperture is about a semi-circle. 



" The outer whorls of this ammonite are rather abundant in a bed 

 a little to the south of Bay town ; but the inner whorls are so decom- 

 posed as not to admit of description." 



Simpson, 1884, 76, the same. 



Remarks 



Stages, conch, serpenticone ; periphery, i ; ornament, 4. It is 

 evident that the words " the radii " should have stood before " very 

 prominent " in the original description. 



This is a primitive Capricorn, and may be the ancestor of the 

 Liparoceratidffi on the one hand, and of Echioceras on the other : the 

 latter is the earlier of the two series, but it carries the development of 

 the periphery further — to stage 5. 



Genus, Androgytioceras, Hyatt, (Gen. Hi) according to present 

 knowledge ; family Liparoceratida, Hyatt. Geological position pre- 

 sumably about L.L. 13. 



Result 



Androgynoceras integricostatum, Simpson sp. 1835, Sinemurian, 

 \oxynotum zone ?], Robin Hood's Bay, near Whitby. 



